Transparency map problems

steven07 · Post by **steven07** » 03 Jun 2010, 09:22

Hey all I'm trying to set a transparency map on a face and I've set it's material transparency to a black and white image and it looks like when I render it only gives me the shadows and not the actual geometry..

To put in more practically.. I'm trying to make a speaker grill-like surface and it's looking like this:

wacom · Post by **wacom** » 04 Jun 2010, 23:38

You might want to try using the sprite shader to get the holes "knocked out" on that texture instead. You'll need to make a matte to drive it if you don't already have one...or you can use the image processing nodes to get a mask (not recommended though). AFAIK, it renders MUCH faster than using transparency.

If you haven't already, you might want to add a slight normal map bump to the edges of the grill holes to give it a little extra added effect.

Good luck and let us know how it turns out - with pics!

steven07 · Post by **steven07** » 05 Jun 2010, 00:05

Hey thanks for the reply! I tried to add the sprite shader but I guess I'm just too new at XSI.. Is there any way I could get a step by step? Thanks!

wacom · Post by **wacom** » 05 Jun 2010, 02:53

You kind of use it at the last step in this instance. Here is an image of a setup I quickly created to show what I mean. For the bump, used to create "edges" for highlights, I just took the same grid procedural and inverted the colors, diffused it a bit, and then fed it through the bump map node. Make sure to check off ENABLE for the matte in the sprite shader and change it to intensity if you're using a the gray scale values of your map.

Preferably you'd just make one simple map for the matte and another for a normal map of just one hole as things would render much more quickly and use fewer resources. This should be easy to do in PS. You'd then just tile the texture. If it's an offset grill you'll need more than one dot per hole though...

The two sided node is just used so that the effect of the sprite shader can be seen better. I just fed the phong shader into a color correction node to change the back side look.

I'm including the scene file too. It's in the 7zip format (which is very good for zipping scene files, tiffs etc.) http://www.7-zip.org/

Use of sprite shader example copy.gif

steven07 · Post by **steven07** » 05 Jun 2010, 07:01

Holy cow thanks so much for the specific reply and the scene file! It was really great to pick apart and see all the little things and how they work.

My next question is: What is a sprite shader? I mean.. technically.. is it a shader that lets you "punch holes" into surfaces? does it just emulate a boole? Is it just a more computer-efficient (render-wise) way to do it?

Again thanks so much for the help:)

steven07 · Post by **steven07** » 05 Jun 2010, 07:07

Also, I noticed that in the color correct node there isn't really a color picker section it's just fed by a number. Is there any way to find out which color goes with which number? Or a way to get a color picker? Thanks!

steven07 · Post by **steven07** » 05 Jun 2010, 07:18

and this is what I came up with

steven07 · Post by **steven07** » 05 Jun 2010, 07:22

and how in the world do you save out a .gif?

steven07 · Post by **steven07** » 05 Jun 2010, 12:15

This is what I get with my project.. it doesn't look very grill-like.. would adding AO help out?

wacom · Post by **wacom** » 08 Jun 2010, 16:56

I just did a screen cap, opened PS, Ctrl-N for a new file that is the size of the paste board...pasted it...cropped it...saved it as a gif.

Why don't you show us the look you're going for with this by using an example of what you're aiming for?

Are you also sure that you're grill sprite matte isn't inverted? Right now it looks like it's showing dots instead of holes.

AO probably isn't going to help IMHO.

If you post that example I might be able to help get you closer- right now things look a little flat due to your lighting setup (which I know is probably just stand in) and the use of what looks like lambert on everything and no reflections, bump edges etc. Are you going for an enameled black metal grill with offset holes?

http://thumbs.dreamstime.com/thumb_94/1161942679IhG5D5.jpg

If you're doing direct lighting techniques (and even if you are not) sometimes the lighting is at least half of what is going to "sell" your object...so you might need a few specular only lights placed just so to bring out the grill.

steven07 · Post by **steven07** » 11 Jun 2010, 10:17

Hey Thanks for the reply!

This is the look I'm going for:

Although your image looked great too. I'm thinking something a bit bigger though. And yes, I'm trying to get the modeling part down before I get into the lighting part, although it might look a lot better in the preview if I added a basic light setup

Thanks again

Transparency map problems

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