Hello,

I made a HP of a Honda CRV 2012 a few months ago (see my website http://www.clarkcoots.com for HP renders) and wanted to make a LP. I'm pretty unfamiliar with the specs of a LP car model. I've read it can range from half a million tris in the newest Forza type racing games, and can go as low 15k tris or lower I'm sure. It's really one of those assets that depends on what game it is for. It's currently sitting at 20K tris. Would love any feedback as to what a good poly count might be, where I can add more polys or optimze current geometry.

Another question I have is how to texture. I figured most of the exterior can be defined by some material shader rather than texturing no? I'll still need UVs for everything for my normal maps. So would it be wise to have 2 UV sets? 1 that has all material only parts (metal, glass, mirror) and will eventually only use a normal map and cube map. And the 2nd UV set for parts that need a Diffuse, Spec, Normal like the dashboard, seats, etc. One problem I see is there are some parts like a Honda logo and license plate on the back of the car thats in the HP but will be baked into the normal map for LP. This would cause problems with the material only shaders. The exterior would have a metal shader but then the Honda logo on the back would have the same shader but needs to be chrome. Is it possible to use a Mask or something have have 1 shader that uses 2 materials chrome and exterior metal...? I might be over thinking all of this... ahh. Is the material only method a good idea? If so I might have to go back and re-model the Honda logo and license plate so I have separate geometry to define different materials.

My output will either be Marmoset or Cry Engine 3... possibly UDK if I get some ideas on shader set up. really any advice would be helpful, thanks!

Hey man, that looks pretty good. Those super-high polycounts you've heard are for cars without normalmaps, which is not what you are doing here. You could actually go a bit lower in count here and there, some geometry exists for stuff that could be handled entirely by the normalmap.
On the other hand, if you're going to put it in UDK, you'll have trouble getting the normals to match that tangent basis, so the only solution is actually adding more geometry, especially to the body, to avoid smoothing errors. Up to you to decide what you go for.

Oh and your highpoly really is pretty good, you know what you're doing. Make sure you showcase some realime texturing witht his project, as most stuff on your website is highpoly software rendering, not too relevant for games.

Hey Xoluil, thanks for the response and the info about the super high poly car models. Thats not the direction I want to take this model though. I see a few places that could be handled entirely with normal map. Perhaps the vents in the interior, I could angle the HP vents for the bake. on the face of the steering wheel, all the speedometer displays, the base part of the stick shift, probably the CD drive/GPS screen. The exterior the trim around the side windows could be merged with the body, springs in the suspension could be removed. Those are a few places I see to lower the count some more.

I'm afraid I'm not sure what you mean by "you'll have trouble getting the normals to match that tangent basis" in UDK. I'm guessing it means the curvature of the low poly doesnt match the high poly close enough so it could lead to shading errors in the normal map? Is that accurate, or is it more something to do with UDK and the way it deals with normals?

Thanks for the encouragement, certainly the goal of my portfolio is to get more realtime game renders in there. so this project is important to me.

Well, the issue is that the tangents that you bake your map for in Max/Maya, are not the same tangents that the model gets in Unreal, the only solution is to create a lowpoly with less harsh shading, so you end up leaving less work to the normal map (so less can go wrong).

@Xoliul - I'm having a hard time understanding what you're trying to get across about tangents in unreal space, vs. in a bake program. Could you explain a little further.

Uhmm, sorry I'm kinda supposing everybody on Polycount knows this.
Here are some topics about it:

http://www.polycount.com/forum/showthread.php?t=68173
http://www.polycount.com/forum/showthread.php?t=97434
Images here: http://wiki.polycount.com/NormalMap?...ders_and_Seams

Thanks for the links Xoliul. Seems like its a problem with 3dsMax to UDK overall, or just the way that UDK renders Normals/shades geometry. I'm actually using Modo for my baking, and I'm still undecided whether I want to use CE3 or Marmoset (UDK was kinda my last option). So hopefully I won't bump into any problems that you mentioned. So far my bakes from Modo from previous projects have looked good in both CE3 and Marmoset. I remember asking Snefer if he had any workflow problems going from Modo to UDK and he said it was a smooth process, though that's assuming he bakes in Modo. I will keep an eye out for any problems regarding tangent basis in UDK though. Cheers

really quick and dirty normal map bake test at 4098. just an atlas projection, about as inefficient as could be. Have to sort out smoothing groups and of course make real UVs then exploded geo for the bake. But I'm pleased how the normal map is picking up the bevels and insets at this resolution, it'll be even better with some symmetrical UVs and better layout.

I also got the tri count down to just under 15,000, which I'm pretty happy with.

Nice test bake, seems to be picking up the details well from the highpoly.
Looking forward to seeing the final bake

4k is a bit excessive though...

agreed Xoliul, its just a test. Reason I went 4K was because I knew the layout of the Atlas map would be terrible, 4 sets of wheel UVS, each seat with its own UVs, non-symmetrical exterior UVs. So I figured once I make my real UVs I can achieve similar quality to the test with a 2K map or so. I might even go 1024x2048 + 512 for wheels if the UV shells work out better that way, if not probably 2K. The final definitely won't be 4K. Do you have a recommended texture size for a vehicle with 15k tris?

Another test bake with proper UVs. Baked at 4k and scaled down to 2K. It's amazing what scaling a 4k to 2k can do as opposed to baking at 2k. I noticed a big difference in the anti aliasing. I'm happy with the resolution i'm getting. I'm going to make a few tweaks to the High poly, import into maya and run UV border to hard edges script + a little clean up. Then another test bake in Xnormal. Then if all is good, I'll do the exploded geometry scene and final bake in Xnormal.

Ok getting the hang of XNormal. Heres my result so far with the Wheel. its 512x1024. rendered in marmoset

whats with the huge seams on the seats and pretty much everywhere on the car..

wheel looks better though.

Originally Posted by Olli.

whats with the huge seams on the seats and pretty much everywhere on the car..

wheel looks better though.

the car was just test bakes in modo to test texture resolution. there wasn't proper smoothing groups, alot of it was hard edged thus seams. I'm importing over to Maya and doing soft/hard edges there and then baking in XN. The final car will hopefully be the quality of the wheel bake.

normal map and AO are 90% done. some clean up to do after the initial bake from XN. Renders in Marmoset. Final model is 12,600 tris

Came across a problem. I have a stepped gradient look in marmoset, from my normal map. I was wondering if this problem is fixable? I thought this would be a problem if it was a compressed JPG or something, but its a 32 bit TGA...

Maybe it is the ao or shadows ? Anyway nice car.

It looks like the error is coming from your normals map. The stepped gradient is that purple area light purple area on the door. Also, don't use 32-bit TGA for your normals map. You only use 32-bit when you have an alpha mask. Normals don't need an alpha channel. Go with 24-bit and don't compress anything.

Either that or you hit the ceiling for 8-bit normal map precision.

No it's not even that, our graphics programmer explained it to me as a "quantization" issue. I really can't explain what it is (it's wayyy too technical for me), but it becomes apparent on smooth surfaces like cars, where the normal map has to do subtle gradients over large area's. Honestly, the only fix I know is to bake in 3DS Max (or maybe Maya), because it replaces these stepping issues with slight noise, which looks a lot better.
Might be worth trying to bake to a higher accuracy format, 16 or 32bits per pixel instead of 8bpp.

This is another one of those reasons why for proper high end cars, you're better off just ditching normalmaps and using more polygons ;)

But that's exactly what I said ಠ_ಠ

Lol, you guys are talking about the same thing in different terms.

The noisy pattern Xoliul was talking about has a name, Dithering.

I've read that If you bake out with higher precision, you can get better results by scaling it down to 8-bits later in Photoshop, because it may have a better algorithm for this than Max.

Crytek supposedly does this all the time and has their exporter handle the dithering and scaling per platform, according to their crysis 2 texture workflow publication.

I haven't tried that though, I'm not modeling things like cars that have super subtle gradients. maybe you could give it a shot?

It could also be that there aren't enough vertices / lines on the base mesh so that it's stretching the normal map info across too much a distance? Like the problem with cylindrical shapes?

Have you tried making a quick test cutting a line down the door and see the result?

Ok so I tried baking from Maya both with Maya and Mental Ray to a TGA, but I had the same result. The Maya bake unfortunately didn't create a noisy stepped gradient to sorta hide it like Xoliul was saying. So I've decided to just paint the neutral normal map value on the side of the car so there just isn't a gradient. Heres a test result below. I'll go back and clean it up, but so far thats the only solution I've been happy with.