View Full Version : normal map in UDK question
05-23-2011, 04:07 PM
Hi, I'm new to Polycount. I have a question about why my normal map doesn't show up on my model in UDK like it does in Maya. I've been making the most simple models just to get the basics of lowpoly modeling and transfer maps down, but any feedback would still be appreciated.
Here is my simple file cabinet modeled in Maya.
A lot of detail is lost when it goes into UDK
Is there something I'm doing wrong or do I just need to change my workflow to preview in UDK first?
05-23-2011, 05:08 PM
it actually looks fine, it just seems like you arent matching the lighting correctly.. it looks sort of like its being diffuse lit. id suggest 2 things.
1. it doesnt look like you have any ambient occlusion in the model, which helps a lot for game-rez stuff, it helps with the detail.
2. use smoothing groups when you export. im not sure how you export from maya but if there is a smoothing groups option.. use it.
05-23-2011, 05:36 PM
Thanks for your response Oniram. Does that mean I should mix in my ambient occlusion map with my diffuse? I thought that Lightmass did its own ambient occlusion, so I should use both?
Really Important. Are you flipping the green channel before importing into UDK when it looks light in Maya?
You will need to do this because UDK uses the green channel opposite of how maya uses it. And that is what I think may be your biggest issue right now.
05-23-2011, 06:28 PM
well unreal does SSAO, screen space ambient occlusion. it basically will apply AO to the scene relative of 1 mesh to another, but it doesnt do well with individual parts of the mesh itself. its typically done in game-rez objects that you make an AO map and multiply it over your diffuse in photoshop.
take a look at the difference between this model with and without AO here.
05-23-2011, 11:57 PM
I tried flipping the green channel, but it didn't do much. I also added in the AO.
The normals are still not displaying the way I would like, especially the details on the inner drawer. I'm assuming this is just a difference between Maya's viewport (which the first image was a screenshot from) and the game engine?
I've tried many different lighting setups and couldn't produce the prominent normals detail of how its appears in Maya. Thanks for your help so far!
05-24-2011, 03:12 AM
Did you make sure to use TC_NormalUncompressed or TC_Normalmap compression on your texture when importing?
05-24-2011, 10:33 AM
also what size normal map are you using?
05-24-2011, 02:58 PM
@PolyHertz: I used TC_NormalMap compression
@Oniram: All my maps are 1024
When adding ambient occlusion do I need to do a bake from multiple perspectives and then combine them? When I did the bake it only made occlusion from one perspective and thus only added occlusion to the front of my model. I guess what I'm asking is does the method in the link you provided bake AO all around the model?
05-24-2011, 03:31 PM
I think the problem could be laying within your normal map itself, and not the engine. If there is a 90 degree angle on any portion of your high poly, trying to put that information into your normal map is not going to transfer. Try beveling the edges on your high poly where that part of the cabinet you want detail to pop out is in, and see if that transfers better to your normal map and thus, appears better in UDK.
05-24-2011, 04:20 PM
Considering that I can't see any shadows being cast from that cabinet, what kind of light are you using to light up your map? If you're using a skylight, then you're doing it wrong as it's just an ambient light (a very sucky ambient light). Place a point light next to the cabinet and see if it brings the normal map to life.
05-24-2011, 04:55 PM
Tristamus: Thanks for the suggestion. I went back and gave my highpoly a little bit more beveling it it helped a lot.
Xendance: I'm using point lights. Lighting never was my strong suit, and I think the lighting was really overblown and that was the biggest problem.
I'm going to learn a little bit more about ambient occlusion and UDK before I move onto to other things. Thanks for all the help guys.
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