Sculptie Stitch Type

 Mesh, MV-SL-Tutorials, Tutorials  10 Responses »
Apr 102010
 

In this tutorial you will learn some unique ways to use stitch types with your sculpties, such as making sculpt ends that are a line instead of a single pinch point.

What are Stitch Types?

Stitch types determine how Second Life interprets the edges of a sculpt map in order to render your sculpted prim.

Plane Stitching

Plane stitching is like a square piece of cloth, or like a sheet of paper. When you select this stitch type, Second Life does not assume that any of the edges of your sculptie will touch each other.

You can manually put the edges together yourself, but Second Life will not try to “fill in” between the seams. This can be useful for things like landscape sculpts and table cloths.

Note that in SL, only one side of a plane mesh is visible.  The other side will be completely transparent.  For example, if you make a table cloth with a plane sculptie, the underside will be invisible.

Cylinder Stitching

Cylinder stitching is like wrapping that cloth around and sewing two sides together, to make it into a tube.  We can still bend and stretch the tube however we want, but now two sides MUST remain together.

When you use this stitch type, if the left and right edges of your sculptie don’t touch, Second Life will automatically fill that information in so that they do. However, the top and bottom may remain open.  You can, of course, close the top and bottom manually (which is something that I do OFTEN!  Keep reading.)

The inside of the cylinder will be invisible, like the underside of the plane.

Torus Stitching

Imagine that we stretch the cylinder so that it’s really tall and skinny, then bend it around into the shape of a donut so that the top and bottom meet.  This is like “Torus” stitching in Second Life, where Second Life assumes that the left/right, and top/bottom sides will be stitched together.

If you use this stitch type and the edges of your sculpt don’t meet, once again, Second Life will attempt to fill in between the edges anyway.

Sphere (default) Stitching

Lastly, instead of making a torus, imagine taking the cylinder and pinching the top and bottom into a single point.  This is Sphere stitching, and is the default stitching in Second Life.  It assumes that the top and bottom of your sculpt map will come to a single point.

If you use this stitch type, even if the top and bottom of your mesh are something other than a point, Second Life will FORCE them into a point anyway.  This is the main reason why sphere stitching is often not the best stitch type to use.

Because all of the ends on Sphere and Torus stitching are closed up, you will never see the invisible side of these sculpted prims.

Using Stitch Types

You might be looking at this information and wondering what the point is. After all, many people seem to get along fine with just the default sphere stitching.  Maybe you can see a use for some of them, like making loop-type objects with torus stitching, or landscapes with plane stitching, but are there that many uses for these other stitch types?

But really, the value in these other stitch types isn’t in their obvious uses.  It’s in the ability to take advantage of these open edges to do things that you might not at first think of.  Take, for example, this collar from a tuxedo set that I bought:

The tuxedo that this came with was in all other respects fantastic.  But you can see how the front ends of the collar are all wrinkled up, like crumpled paper.  Now look at a shirt collar that I made for one of my own outfits:

The ends of my collar aren’t perfect, but they don’t have the crumpled look.  The crumpled ends are a result of the stitch type used to create it.  The first collar uses the default sphere stitching.  My collar uses cylinder stitching.  Let me show you.

To make a collar in Blender, I often start out with a cylinder that’s been modified into a sort of flat, long shape, like the image on the left.

In order to make a shirt collar from this, we need to curve it in two directions.  First, to make the arch of the collar, then to curve it around the neck.  These two curves make collars a particularly interesting challenge for a sculptor.

So lets think about stitch types.  Default stitching is Sphere stitching, which forces the ends to pinched to a single point, so lets do that to the ends of the mesh.

Now lets create the arch of the collar.  Switch to the side view, looking at the new stitched ends.  Select all of your vertices (tap A) and place the 3D Cursor (that circle thing with the cross-hairs) somewhere below the mesh (place it by left-clicking inside the 3D window.)

Now press Shift-W to Warp the mesh around the 3D Cursor.

You can already see a problem.  Because all of the end vertices come to a single point, instead of a nice arch the ends look something like the image above.

We could try using a few edge loops to push around the edges and force the ends into arch, like the image on the left.  That’s what the creator of that tuxedo set did and that’s where the crumpled edges on that first collar came from, so it ends up looking kinda ugly, not to mention the wasted edge loops.

So what can cylinder stitching do for us?  We may not want the ends of the collars to pinch, but we also don’t want them open, showing off the invisible inside.

I’ve already told you that we can force a cylinder’s ends closed.  For example, we could manually pinch them off, like sphere stitching, but that doesn’t do us much good.  But what if we close off a cylinder in a way that we COULDN’T do with sphere stitching?

Here, instead of pinching the ends off to a point, we only pinch them in one direction, creating a seam – a line of vertices.  This still effectively closes off the ends, but in a much different way than what we could get with sphere stitching.  Look what happens when we curve the mesh.

Now we have a much nicer, clean edge to work with.  If we bake this sculptie and import it into Second Life, if we select Cylinder stitching on the new sculptie, we will also get this line seam.

Aside from collars, this sort of  straight-line edge can also help with texturing.  Look at these two beveled cubes.  The one on the left has default sphere-type stitching.  The one on the right was built to use cylinder stitching.  This makes for a much nicer texture layout.

If you aren’t convinced yet at the power of different stitch types, let me show you a few examples.  I won’t tell you exactly how they’re done or why I used the stitch type that I did.  Instead, look at them and try to figure it out for yourself. As always, I’m not an all-knowing expert.  You may see a better way to do things than what I’ve done, but this may give you some ideas anyway.

Stitching Examples:

Think outside the box.  There are tons of ways to use stitch type to your advantage, to create shapes that you normally couldn’t create, or to clean up a mesh that has nasty ends or texturing issues.  If you do something particularly neat, you might consider showing it off in the new forums.

Add Alpha Protection to Sculpt Maps

 Mesh, MV-SL-Tutorials, Tutorials  23 Responses »
Mar 252010
 

In this tutorial, you will learn how to add an alpha channel to your sculpt map to protect it from theft by screenshot and how to add a watermark to the alpha channel to let people easily tell that you made it.

A Thief!  A Thief!

Many people don’t like to include modify permissions on their merchandise to protect themselves against theft, however, there is a way to protect your sculpties from theft and STILL include modify permissions.

The easiest way to steal an object’s sculpt map is the screenshot method. The thief opens up the edit window, clicks on the sculpt map, and then takes a screenshot. He’s then free to crop the sculpt map from the screenshot and re-upload it into Second Life.

However, there’s a cure.

The Theory

Any builders will probably be familiar with Alpha Channels in Second Life. If you’ve ever seen a wall texture with window cut out of the middle, this is done with an Alpha Channel. Second Life textures can use alpha channels to add transparency to an image – but the transparent parts can still retain their RGB values! So in theory, you can create a completely transparent sculpt map that still has the RBG data necessary to form your sculptie.

Only in theory?

Well … it really depends on your image editing software and the file format you choose to save in. In my experience, only Photoshop and GIMP can do EXACTLY this. Other applications can get close enough, though.

Application-Specific Guides

After trying to help my sister reproduce alpha channels in Paint Shop Pro and Gimp, I’ve come to the conclusion that every image editor does this so differently that I need to create a guide for each one.

Photoshop
Photoshop Elements
PaintShop Pro
The GIMP

Watermarking

You’ve probably seen sculpt maps that have a logo or other watermark cut into the map image.  I’ll show you at least one method to do this in each application.  To make this process easier, I have a 64 x 64 black and white version of my logo (without the text) that I use specifically to watermark sculpt maps.  I’d recommend that you make one for yourself, as you can use this directly as an alpha channel, or to select an area to cut out of layer.


Alpha in Photoshop

To add alpha protection to your sculpt map in Photoshop, you have to use either the TGA or PNG file formats. How you add the protection depends on which file format you decide to use.

TGA Format

The TGA format in Photoshop is the most direct and (in my opinion) easiest method for adding an alpha channel to a sculpt map.

All we have to do is go into the channels menu (shown left) and hit the “New Channel” button on the bottom of the menu. (It looks exactly like the New Layer button in the layers menu.)

By default, Photoshop will make a solid black alpha channel.  This will make your image completely transparent, which is fine.  I, however, chose to paste a black and white version of my logo into the channel so it will show up on the sculpt map when I upload it to SL.

Now save the file as TGA. Photoshop will bring up a dialog, asking you a few things. Just make sure that it’s set to 32bit. Nothing else matters. Save and upload into Second Life.

PNG Format

As much as I prefer TGA alpha channels, there are people who swear by PNG format because.. well, you can see the transparency directly on the image, rather than having to interpret the alpha channel.

But NOTE to png users. In order to make the file size smaller, Photoshop does NOT save RGB values for completely transparent pixels in a PNG image. So if you use PNG, all of your pixels have to be at least slightly visible.

In the Layers menu, make the background layer into a normal layer. This can be done by double-clicking the background and hitting “OK” on the dialog that comes up.

Now change the opacity of the layer to 1% or higher. This will still keep your sculpt map from being stolen while forcing Photoshop to save the RGB information to the sculpt map image.

In order to get my logo on this one, I created a duplicate of the sculpt map layer, turned the opacity up to 100%, then cut my logo out of that top layer.  Then hit CTRL-E to merge the two layers

Save as PNG with no interlace and upload to Second Life.

Alpha in Photoshop Elements

To add alpha protection to your sculpt map in Photoshop Elements, you have to use the PNG file format.

In the Layers menu, make the background layer into a normal layer. This can be done by double-clicking the background and hitting “OK” on the dialog that comes up.

In order to make the file size smaller, Photoshop does not save RGB values for completely transparent pixels in a PNG image. In order to retain the RGB data, all ot the pixels need to be at least slightly visible.

So change the opacity of the layer to about 1% – NOT 0%. This will still keep your sculpt map from being stolen while forcing Photoshop to save the RGB information to the sculpt map image.

In order to add my logo watermark, I created a duplicate of the sculpt map layer, turned the opacity up to 100%, then cut my logo out of that top layer.  Then hit CTRL-E to merge the two layers.

Save as PNG with no interlace and upload to Second Life.

Alpha in PaintShop Pro

To add alpha protection to your sculpt map in Paint Shop Pro, you can use either PNG or TGA. How you do this is dependant on which file format you choose.

PNG Format

Open your sculpt map, then find the Layers palette on the right. Near the top, there’s an opacity slider for your background layer. PhotoShop will not save the RBG data for completely transparent pixels, so slide the opacity down to 2 (NOT 0!). (When you do this, your background layer will be changed to “Raster 1″ or something similar.)

You can leave the file as is now, or you can add a watermark. Duplicate the sculptmap layer, switch it to 100% opacity and cut out your logo or text.

Now re-save your sculpt map in PNG format. Upload into Second Life.

TGA Format

Typically, in Photoshop, I like working with TGA alpha channels, just because you can retain all the color information in your image, even when pixels are completely transparent. The problem is that, in PSP, I have yet to find an easy way of viewing the alpha channel once one has been created, which makes things frustrating.

However, if you’d still like to use the TGA file format, here’s how.

Open your sculpt map. In order for this method to work, you need to select at least one pixel in your image. Do this however you want. The area you select will be visible in SL, so don’t select everything.  A neat idea would be to select an area shaped like your logo.

Next, go to the top menu and click on Selections > Load/Save Selection > Save Selection to Alpha Channel. PSP will give you a dialog, but the default settings should be fine. Hit Save.

Now go to File > Save As and save the sculpt map in TrueVision Targe (TGA) format. You may get a warning about only saving one alpha channel. Click Okay.

Now upload the sculpt map into Second Life. Part of the sculpt map will still be visible (the area you selected), but it won’t be enough information for anyone to steal your sculpt by the screenshot method.

Alpha in The GIMP

To add alpha protection to your sculpt map in GIMP, you can use the TGA or PNG formats.  Both formats work nearly the same.

PNG and TGA Formats

Open you sculpt map in Gimp, then open the Layers and Channels dialogs by going to the image menu and selecting Windows > Dockable Dialogs > Layers and Windows > Dockable Dialogs > Channels.

Now select Layer > Mask > Add Layer Mask.  You’ll get a dialog that asks what you want the layer mask to look like.  For now, tell it to give you a completely black mask.  Hit Add.  Now you’re layers dialog will look something like the image on the left

This new mask is completely black, which will make our sculpt map completely transparent.  If you’d like, you can use this mask as-is, but I’ll run you through an optional step to add a watermark to the sculpt map.

Open up your logo or watermark file, select it (CTRL-A) and copy it (CTRL-C).  Now in your layers dialog select the layer mask (NOT the layer itself!) and paste your logo (CTRL-V).

At this point, you will see the watermark on the sculpt map in the image window, but the selection will still be ‘floating’ in the layer dialog.

Right-click on this floating selection and select “Anchor Layer”.  This will de-float the selection, and you should see your watermark as the layer’s mask.

Finally, right click the layer mask and select “Apply Layer Mask.”  Your layer mask will disappear from the layer dialog, and be added as a fourth channel called Alpha, which you will see in the channels dialog.

Now you’re ready to save your sculpt map as either a TGA or a PNG file.  Oddly enough, this is the only step that’s different for the two file types.

For TGA files, you only have to save the image. It will bring up a small dialog, but it doesn’t matter whether or not you use RLE compression, as SL will re-compress the image anyway.

For PNG files, you’ll be presented with a larger dialog.  There are two options that you should pay attention to.

Find “Save Background Color” and un-check it.

Find “Save color values from transparent pixels.”  This is usually checked by default, but just make sure that it is.

The rest of the default values should work fine.  Press Save.

You’re finished! Upload your protected sculpt map into Second Life.

Oblong Tessellation

 Mesh, MV-SL-Tutorials, Tutorials  No Responses »
Mar 222010
 

In this tutorial you will learn how to use Oblong Tessellation to get better results with long, skinny sculpts like pipes and chair frames. I use Oblong Tessellation for many other things too, so it’s a useful tool to add to your own knowledge.

The Long and Short of It

A lot of you probably looked at the term “Oblong Tessellation” and went cross-eyed.  Don’t worry. I did too.

But after looking into it, I figured out that it’s just a freakishly complex name for a pretty simple concept.  All we’re doing is rearranging the sculptie’s vertices so that instead of a perfect square 32×32 grid, we have a rectangular grid at 16×64, or 8×128.

Above, you can see the difference between a normal sculpt map and one that uses oblong tessellation.

Why is this useful? Let me break it down for you.

The Pipe Problem

Lets say you want to make a sculptie pipe to import into Second Life. You want this pipe to be long, skinny, and as windy as possible. You decide to use three edge loops per bend to keep the pipe looking nice.

Using the default 32×32 mesh, you come up with something like the image on the left. You wind up with nine or ten bends, which is okay, but not as bendy as you’d like. (Note that if you had accounted for any amount of LoD, you’d have even less bends then that!)
Now take a look at the cross section of this pipe and you’ll begin to see the problem.

There are 32 points on every edge loop, which is a problem in more than one way.

First of all, you don’t need 32 vertices to make something that skinny look round. These are wasted vertices.

Second, sculpties start doing weird things when you have a lot of vertices in a small area. The more points you have in a small area, the more chance you have for jagged edges when you import that sculpt into Second Life.

So. What do we do? We make an oblong sculptie! This is pretty easy to do. When you bring up the dialogue to create a sculptie, by default it shows 8 x 8 faces with 2 levels of multires. Change this to 4 x 16. When you enter the number for Y, initially, it will turn black and the Build button will be greyed out. Usually this just means the dialog wants you to press Enter so it can recalculate your sculpt mesh.

There are a lot of different sizes that you can make your sculptie. For a complete list, look here. Sizes are listed as (face)x(face)x(multirez). However it doesn’t seem like Second Life can handle all of these sizes correctly. The only sizes that I’ve gotten to work (at least with with anything practical) are 8×8(x2) and 4×16(x2), and 4×64(x1).

Look at the cross section of this new sculptie.

Now each edgeloop has half the number of vertices, which is still plenty to make it look round. We aren’t wasting nearly as many points, and we won’t have so many problems with edges becoming choppy.

What’s more is, those points we took from the diameter of our edge loops now go into making the length of the pipe. We can add even more bends. (Or we can work with multires so our pipe doesn’t loose it’s shape at a distance.)

Look at the difference between our original pipe and the oblong pipe. We have a lot more to work with. This doesn’t just apply to pipes. It’ll work for anything that has a long, skinny shape, like the frame of a dining chair, or scaffolding for a building, or a streetlamp, or a pencil twisted in the shape of a heart!

Baking an Oblong Sculptie

Domino’s new primstar scripts automatically assigns your mesh an image sized based on the faces and and subdivision levels that you started with.

So if you started with a mesh with 8 x 8 faces and 2 subdivision levels, it will assign a 64 x 64 image.

If you start with a 4 x 16 mesh and 2 levels of subdivision, it will assign a 32 x 128 image.

In previous versions of my starter tutorials, I instructed people to start without subdivision levels (no multires) because I felt it was easier ( and I STILL feel it’s easier) to start defining a mesh with less vertices.

However, if you start with an 8×8 mesh and no subdivision, your mesh will be assigned a 16×16 image, which isn’t what you want. So now it’s better to start with the 2 levels of subdivision and then manually delete the higher levels if you wish to start with a simpler mesh.

Tips, Tricks, and Notes

Oblong Tesselation is still rather new and while I use it all the time now, I can’t, for the moment, think of any tips specifically related to it.

But as a note, there is some functionality of oblong tessellation that’s still being developed. Particularly the ability to use LESS vertices than the current 1024, which would be useful for certain simple geometric shapes.

Multi-Sculptie Builds

 Mesh, MV-SL-Tutorials, Tutorials  42 Responses »
Mar 212010
 

In this tutorial you’ll learn how to make objects with more than one sculptie in Blender, and import all of it into Second Life, plus how to make duplicate sculpties in your blender file.

E Pluribus Unum

Sometimes it’s necessary to build an object with more than one sculptie. A knee-high boot, for instance, may need to be attached to more than one bone on the SL skeleton, or an object may have clearly different pieces like a belt and a buckle or a sword with a sheath, or a shape may simply be too complex to do easily with one sculptie.

You can model all of the sculpties you need in the same .blend file to be sure that the two sculpties fit together, and to do useful texture tricks, like having the sculpties cast shadows on each other. (See this tutorial)

Primstar Scripts

Domino’s new Primstar scripts actually include the ability to export multiple sculpties with a script that will let you recreate a multi sculpt object in Second Life.

Once you have things finished the way you want in Blender, bake the sculpt maps for all the sculpties you want to export. Next, select all the sculpt meshes in Object Mode, making sure the root prim is highlighted in bright pink.

Press Ctrl-P and select “Make Parent”. Double check that the other meshes are parented by selecting just the root object and moving it around. If the other objects follow, you’ve got it.

With that root object selected, go to the top menu and select File > Export > Second Life LSL (to dir). Browse to a folder (preferably an empty one) and hit ‘export’. This should save all of your sculpt maps and ONE plain text file with the extension .lsl. Open this lsl file with a program like Notepad, select all the text and copy it.

In world, rez a plain cube on the floor. Upload all of the sculpt maps and add them to the contents of your box. Next, create a new script inside the box, then double-click the new script to edit it. Delete the default script and replace it with the text you copied from the .lsl file.

Hit Save, and after a few seconds, the script will ask you to create a prim, name it “Primstar” and put it into the box. Do that. Then the script will ask you for linking permissions. Once you give the permissions, the script will start recreating your object in world, ending by linking everything together.


Duplicating a Sculptie

If you want to make a single sculptie that will be used on multiple parts of your build, go into Object mode and press Alt-D. And move the new object to where you want it.

This will create a new object, but the mesh for both will remain identical. If you edit the mesh in Edit Mode, both objects with change. If you scale/rotate/move the object in Object Mode, it will only effect the one object.

If the shape you need for a new sculpt mesh is similar to a mesh you already have, but not identical, go to Object Mode and press SHIFT-D instead. This will create a copy, but both the object and the mesh will be separate, so you can edit the new one without effecting the old one.

Currently, the Primstar scripts don’t seem to understand exporting objects with duplicate sculpts. I tried exporting a skull that used a lot of duplicate sculpts for the teeth, and that broke the lsl script pretty bad. xD So keep that in mind if you’re planning on using it.

Adding a Mesh from an Older File

If you have a sculptie from a previous file that you’d like to add/edit in your current one, you can ‘append’ the object.

You may want to save your current file now, in case of error. Now we’ll be using a function in Blender that lets you browse inside another .blend file and select a part to add to your current file. Go to File > Append or Link.

From here, you may actually start inside your current .blend file, which is useless because Blender doesn’t let you append anything from inside your current file. (Can someone explain to me why Blender does this?) Hit “..” until you see the contents of your save directory, then find the .blend file that contains the mesh you want to append and click it, then click “Object”. From here you’ll see a list of the objects in that file. Hopefully you’ve renamed your sculptie objects so that you can easily identify them. Select the one you want, and click “Load Library.”

If you haven’t been doing it already, it’s good practice to rename your objects in Blender

This makes browsing with the Append feature easier, and also lets Primstar name your sculpt maps or you before you export them to your hard drive.

Make One Sculptie Look Like Two… or Three… or Four

 Mesh, MV-SL-Tutorials, Tutorials  8 Responses »
Mar 212010
 

In this tutorial, you’ll learn how to make a single sculptie look like more than one object.

Making the Cut

If you look at the image here, the cushions on this chair are both the same sculpted prim. They are connected by a tiny, invisible line of points. I’ll be showing you how to do just that. Before you read this tutorial, it’s recommended that you go through the Precision Sculptie tutorial.

The method was developed by Aminom Marvin.

The Long and Short of It
(Or… just short)

Okay. You want to know how to do this? I warn you. You will gawk at the simplicity.

Select one loop of vertices and scale it to 0. (You can scale to zero easily by tapping S, then the number 0.)

Then select the loop just above or below and scale it to 0 as well. Be sure you deselect the previous loop. (Did you know that you can select a loop in Blender by holding ALT and right-clicking on one of the edges in the loop?)

Congratulations! You just made a fractional sculptie! If you bake this and import it into Second Life, it will look like two separate objects. Maybe

Maybe? Yes. The pole may still show up. It will be thin, but it will be there, until you snap the vertices to the Precision Grid!

The Precision WHAT?

If you have no idea what I’m talking about, you need to read through the Precision Sculptie tutorial. If you have read it, you might want to run through it again real quick, cause I’m not going to repeat much here.

Just remember that you need to set the grid to .01, scale the object to 2.55 x 2.55 x 2.55, line it up to the grid, then snap your vertices to the grid. After you’ve done this, you can bake your sculpt map and import it into Second Life and you should have completely invisible poles.

Tricks, Tips, and Notes

For simplicity’s sake I’m going to be referring to the separate sections of a fractioned sculptie as “pieces.” So in the first example in this tutorial, the sculptie would be separated into the top piece and the bottom piece.

Trick: Half Poles

If the one-point poles are taking away too many points for you, sometimes you can get away with using what I call ‘half poles.’ This only works if an end of one of the pieces will end up inside of another piece – hidden. Like…. THIS:


A brief summary of what’s going on here. I only pinched off a single loop, instead of two, then cap off the piece that will have the visible end. Then I resized the other piece so that the end would fit inside the capped piece (reduces clipping and other uglification problems). Then I rotated the smaller piece and repositioned it so that the connected end is now inside the larger piece. All the crap in between the two ends is inside the larger piece. No one’s going to see it, unless they’re trying to figure out how you made your awesome sculptie.

Tip: Don’t do it when you don’t need to.

I’ve seen a few people use Fractional Prim Modeling in cases when it’s really not necessary. Like… if you’re making a 1-prim sculptie hamburger, you probably don’t need to completely separate the patty from the buns. You’d just end up wasting vertices.

Often times you can get better results by using other methods to visually divide a sculptie. Be smart about it.

Resolution Tricks

 Mesh, MV-SL-Tutorials, Tutorials  3 Responses »
Mar 202010
 

In this tutorial, you will learn some tricks to make your sculpties looks better at a distance, including the “shrinkage” trick.

LOD Can Kill

As you already know, sculpted prims switch between three resolutions depending on your camera’s distance from them in Second Life.

Sometimes the difference in resolution makes such minor differences in the sculptie that you can simply ignore it. However, sometimes the lower LOD levels end up looking bizarre, or you may simply want the sculptie to retain its resolution better.

The sculpties in the image above were all the same mesh in Blender, but the sculpt map image was changed to effect how the the resolution held up at different distances. The screenshot was taken with Object Detail in SL’s Preferences turned almost all the way down.

Remember Multires

Before I get into more technical tips and tricks, I want to remind you about the multires feature in Blender. I had you learn about that for a better reason than just to annoy you. Multires corresponds with Second Life’s LOD (Level of Detail) rendering.

If you start off modeling at the 8×8 resolution (level 1) then your sculptie will have a better chance of retaining it’s basic shape. At the 16x 16 resolution, you should try to include as much detail as you can. The 32 x 32 resolution should only add the most nit-picky details.

If you don’t remember anything about multires, go back to the multires tutorial and read up.

Texture Tricks

Often you can make the decreases in resolution less noticeable by using a high-quality texture on your sculpties. Baking on shadows, for instance, helps to visually define a form, which will make your object appear to be higher resolution than if you were relying on Second Life’s realtime shadow rendering.

To learn more about texturing sculpts in Blender, read this other tutorial.

Shrinkage

There is a more technical trick that will actually help keep your sculpt’s shape at greater distances.You can shrink them.

I don’t mean in SL. In Second Life, you’ll actually be making them bigger.

An Explanation

You see… the distance at which your sculpt loses resolution is relative to how large the sculpt is. The larger the sculpt, the farther away your camera can get before it loses resolution.

So, what we want to do is make the sculpt larger, but make it appear to be the same size.

Yeah, I know. Weird. But it can be done. You’ve probably seen sculpts that do something like it. Several of the freebie sculpts floating around don’t quite fit inside the bounding box when you scale them. Have you noticed? You can stretch and stretch these sculpts, but they they never seem like they stretch far enough! Well we’re going to do this on purpose.

Using Primstar

The new Primstar scripts allow you to shrink your sculptie when you bake the sculpt map.  When you bring up the Bake Sculpt Meshes dialog, you’ll see a box on the right marked “Range.”  The default values for each color value (or axis) are 0 to 255.

What you want to do is increase the values on the left and decrease the values on the right by the same amount.  I chose to increase the left values by 55 and decrease the right values by 55, because those numbers are easy to figure out.  (I’m lazy.)  The larger the difference between the original values and the new ones, the more your sculptie will shrink.

Image Editor Method

You can also do the same thing with some sort of image editor like Photoshop and decrease the color contrast. Some experience in Photoshop is recommended, because I’m going to describe how to do things in Photoshop, since I have practically no experience in any other image editing software.

Open your sculpt map in your image editing application. In Photoshop, the next step is to go to Image > Adjustments > Levels. Ignore Input Levels. You want to change Output Levels, and it needs to be changed by the same amount on both sides. The default values are 0 and 255. Once again, I usually change mine to 55 and 200 since those are easy numbers to figure out. And still. the greater the difference in the new values from the default, the more your sculpt will shrink. Once you’ve decided on your values hit ‘OK.’ Your sculpt map will look slightly greyed.

In some programs, you can use Brightness/Contrast and decrease the contrast, but this is less precise, and it doesn’t seem to do the same thing in Photoshop at all.

Upload your sculpt map and apply it to a sculpted prim. You’ll see it shrink. If you have the original sculpt uploaded, try placing the two next to each other, and stretching your shrunken sculpt so it looks the same size as the original. Then zoom out and watch how their resolution changes.

A Word of Warning

Although this is a neat trick, you can decrease the contrast on the sculpt map too much.

First of all, if your sculpt is not made phantom, the collision box will be as large as the bounding box, not the shrunken sculpt, but also, your sculpt can become deformed.

The image on above shows the same set of sculpts as the first image on this page, only with the Object detail in SL’s Preferences turned to Mid. Notice that the first two sculpts look identical. The third is slightly more choppy looking, and the fourth, obviously, is rather deformed. Below is what the sculpt maps look like:

The less contrast there is, the more values start to run into each other and the more choppy your sculpt will be. If you’ve done a good job with multires and texturing, there usually isn’t any reason to even get as shrunken as the third sculpt. Remember to use this trick wisely. Only when you absolutely need it, and only to the degree it’s needed.

Create Precise Sculpted Prims

 Mesh, MV-SL-Tutorials, Tutorials  10 Responses »
Mar 182010
 

In this tutorial, you’ll learn about the sculptie grid, how it effects your sculpts, and how you can place vertices of your sculpt mesh with precision.

For Your OCD

Usually, when you’re creating simple and organic shapes, using basic sculpting techniques works just fine.

However, if you want to make complex and highly precise sculpts, you may run into some problems with things like getting shapes perfectly symmetrical, or getting a shape to curve without getting jagged edges.

But you can get very accurate and smooth sculpted prims with the tools available in Blender, some advanced knowledge, and a little bit of patience.

Precision sculpting techniques can be used for creating:

Smooth, professional-looking archways
Complex, geometric shapes, like gears
A single sculptie that looks like multiple objects (see this tutorial)
Any other shape that needs to be highly accurate.

An understanding of the principles behind precision sculpting can also help you create cleaner meshes and avoid problems that might otherwise make your sculpties turn out looked jagged or distorted.

The Theory

You already know that a sculptie’s shape is defined by an image’s RGB values.

Consider this:

How many values are available in an RGB image. The total number is quite large, but for each individual channel, the answer is 256. Values range from 0 to 255.

So. Translate this to your sculptie. How many locations are available for the points of your sculpt map. It’s the same number as the available RGB values. There are 256 available location-values for each axis of your sculpt.

Think of it as a 3-Dimensional grid. 256 x 256 x 256. Then think of a ‘snap to grid’ function. If the points of your sculpt don’t fall on one of these grid points, when you bake your sculpt map, the points will be put at the NEAREST possible point. For most organic sculpties, this is fine, but if you need a precise sculpt, often this will put points far enough off the mark to make the sculpt look… bad.

Note: You decrease the number of available locations when you decrease the contrast of your sculpt to \’shrink\’ it, as this eliminates a good number of the RGB values that get used.

The Practice

So what we are going to do is actually set up this grid in Blender. Then, when we have the sculpt finished we can snap all the vertices to the grid, so that every vertex will be placed exactly how it will be when imported into Second Life.

For this part of the tutorial, open up a .blend file with a sculpt mesh that you would like more precision on. For the purposes of this tutorial, try to use a sculpt that is relatively simple, and has some sort of curve to it. Something like an archway or the hood of a VW Beetle would be good. I’ll be using the beveled archway shown above.Go to the menu below your 3D View window and navigate to View > View Properties. In the dialog that pops up, change the Grid Spacing to 0.01 and the Divisions to 1.

Make sure that you’re in Object Mode and select your sculpt mesh object. Then go to the menu below your 3D View window and navigate to Object > Transform Properties. Alternatively, you can just tap N.Change the dimensions of your object to 2.55 x 2.55 x 2.55. This will probably make your mesh look distorted, but what we did here is make it so that each .01 grid space represents a value on each 0-255 axis. At this point, my beveled arch looks like this:

Lastly, you want to place a corner of your mesh on the grid. Find a point on your mesh that makes a good “outer corner” of your mesh, such as one of the bottom ends of my arch. Zoom in so you can see the grid, then line up the corner with one of the grid points ( as shown here).

Now, if I was to snap the vertices to the grid right now, (Mesh > Snap > Selection to Grid) the results would look something like the mesh on the right:

You can see how the lines of vertices become rough. If I had exported a sculpt map from the mesh on the left, this ‘roughing up’ is exactly what would have happened. So what do we do? We perform an exercise in patience. We place our vertices on the grid BY HAND!

Don’t worry. You don’t need to place every single one on a grid point. Just the ones that are significant to defining the form of your mesh. For example: On my arch, the vertices that define the form the most are the ones that make up the top and bottom edges. The ones in between aren’t so important.

Shape reference

In order to make things slightly easier, I’m going to make a duplicate of my object that will act as a shape reference for my final piece.

Go into Object Mode (TAB). Hit SHIFT-D to duplicate, then RClick to place the duplicate mesh at the same location as the original. Now go back into Edit Mode (TAB again).

In this image, I’ve pulled one of my ‘significant’ vertices down so you could see the reference line provided by the duplicate mesh.

What I want to do is place the vertices at points on the grid that intersect with the reference line (like the point marked with the yellow arrow.
Do this for all your significant vertices.

In the end, your mesh may look something like the image on the left. I have marked all of the vertices which I placed on the grid. All other vertices shown were placed arbitrarily.

Now, snap your vertices to the grid, then bake your sculpt map.

The vertices kinda look like a mess, yeah, but in the end, you keep the shape of your object better than if you had left your mesh in it’s original state. To emphasize my point, and also show off what precision sculpties can do, here is a screenshot of my finished sculptie in Second Life, below it’s closest equivalent made with regular prims. You can click the image to see it larger:

Tricks, Tips, and Notes

I’m still learning about precision sculpting, but as I gain tips and tricks for making precision sculpting better and faster, I’ll add them here.

Trick: Mirrored Halves

If you have a precision sculpt that has symmetrical halves, you can cut down on some of the placement work by using a mirror modifier. (Click here to learn how.)

With the mirror modifier in place you can go through and place the vertices on the one half of your sculpt, and the modifier will do the other half for you.

Note: After you’ve applied the modifier, you will have to move the vertices on one half inward by one grid space  so that the sculpt’s dimensions are still 2.55 units cubed. Now snap your vertices to the grid, then export the sculpt map.

Tip: Default Settings

If you find that you’re using the precision grid very often, you can add the grid to your Default Settings. Just set everything up how you want it to look when you open up Blender, then navigate to File > Save Default Settings.

Note: Shrinkage Resolution Trick

If you’ve already read my tutorial on Resolution Tricks, you’ll probably remember the section on shrinking a sculpt. When you do this, you are giving up a chunk of your possible placement points.

For example: If, in the Levels dialog, you put the sliders to 50 and 205 (default is 0 and 255) You are taking off 100 possible placement values for each axis. If you know you’ll have to do this resolution trick, plan ahead. Instead of sizing your mesh to 2.55 cubed, you’ll have to size to 1.55 cubed.