bob...there's something fishy going on!

Hello again. Today we'll tackle part two of my 3 part tutorial. Last month (if you were paying attention) we modeled the fish using NURBS. Hopefully your model came out well and you are ready for this week's topic: Texturing.

One of the reasons that we stuck with NURBS surface with our fish is that NURBS and patch surfaces can be really easy to texture as long as you are careful during the modeling process (which we were). NURBS and patch surface can be UV textured. That means that the texture can be stuck right to the surface of the model rather than projected on to it. For example, here are two cubes with a picture of London mapped onto them.

The upper cube is made from polygons and has a projected texture map. You'll notice that the map is all smeared on the sides. The other is a NURBS cube with a UV map on it. The UV map is able to stick to the surface of the cube and map properly in all directions. We'll be using UV mapping for most of this project, and now that you've had a little UV primer we can get busy!

I wanted this fish to look realistic, so the first step was to go out and get a fish to slap on the scanner. I'm including the scan I made so that no more fish need to die needlessly.

Click here to download a large TIF [4.31Mb]

Scanning in real objects is a great way to get raw material for textures. Jeremy Birn has some excellent examples on www.3drender.com. Look under "Productions" and then "Entry Tunnel".

Once your fish is scanned in, the first step is to make the basic skin texture that will go over the body of the fish. I cropped a section out of the fish scan and tweaked it up in Photoshop. I used the clone tool to even out the texture and then I copied and flipped it so that it was symmetrical along the x-axis.

Click to download a large JPG

Next, I made a bump-map to accompany the skin texture. I made it by using the lighting effects tool to bring out the bumps and then adjusting the levels to increase the contrast. I also added a stripe down the sides to help bring out the stripe in the skin texture.

Click to download a large JPG

With this step done, you can go into Softimage to apply the texture. The material must be set up first. I used a phong with a very high specular highlight (1000) to try to get the "wet look".

I applied the skin map first (using UV mapping of course!) and set the specular all the way up but keep the ambient and diffuse down around .6 or .7. I also had to translate the map in x a little bit so that the backbone area of the map lined up with the backbone of the fish. The bump map comes next. I applied it using the same x offset as the skin map. I turned the ambient, diffuse and specular down to zero but kept the overall blending up at 1 (so that only the bumps show). I turned on the displacement map option and set it to .02 so that I only got a slight bump.

Here's what it looks like so far:

The head is next. Again, I cropped some juicy bits from the original fish scan and did some Photoshop work on it.

I also made a special map for the gills. I cropped out the gills and then made an alpha channel so that only the central part of the map will be opaque.

In Softimage I gave the head the same material as the body. I mapped the head as before, using a skin map and a bump map. I also added the gills using a YZ projection with an alpha channel. Buy doing this, I'm able to just Slap the gills on the side of the fish's head, and the seams of don't show because the edges of the map are transparent. Here's a shot of the head.

To do the spines, I first made a simple ramp from dark blue to tan in Photoshop.

So far, so good. Now it's time to map the 80 or so spines that we have on this darn thing. Actually, it's not as hard of a job as it may appear to be. If you multi-select all the spines and hit the "Material" button in the Matter module you can apply materials to all the spines at once. I used a very dark blue phong with a high specular setting. If you open the schematic window now, you'll notice that you have 80 some-odd materials, one for each spine. To remedy this very inefficient situation, you can simply hit "Mat_Oper>Optimize All" in the Matter module. Now you have one material for all of the spines.

The secret to mapping all of these spines is to map one and then copy the map to all the others. I picked one spine and UV mapped the color ramp onto it.

Then I selected all the other spines and hit "Tetx_Oper>Copy All" in the Matter module. I then clicked on the first spine, the one I textured. You'll have to click Ok for all the textures, but it's allot better than mapping each spine individually.

The last step is to do the surfaces of the Fins. I made a ramp alpha channel so that the fins would get more transparent out at the end. The map I made in Photoshop looks like this.

For the fin material, I used a basic phong. I applied the fin texture and used the alpha channel for transparency. I copied the Texture over to each fin and rotated the map so that the transparent part pointed out. Here's a peek at them.

The eyes are UV mapped. You can just "pluck" them from the scan (he he).

All done! Here's a shot of the textured beast.

Good job! Now pat yourself on the back, enjoy a tall glass of your beverage and admire your handiwork. You can also look forward to next month, when we'll animate this guy and send him on his way using particles.


Peter Arisman is a digital artist working and living in Seattle. He can be contacted at reepete@geocities.com and has a web site at www.3dartists.com.

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