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View Full Version : Latest car render, any thoughts?


Hakushinkan
07-21-2010, 01:51 PM
Hey guys.

I've been working extensively on Mental ray these past couple of weeks. This is the first full project I've ever done in mental ray, and I've been using it for about 2-3 weeks, if you don't count very basic knowledge I've been carrying around for a month or 2 before that. Until now I concentrated more on the modeling side.
This is what I could come up with eventually:
http://lh3.ggpht.com/_NEkwN1SfiXw/TEblH2KtPII/AAAAAAAAAOg/9xAFDUQ2XQQ/s912/CarRealistic2.jpeg
http://lh3.ggpht.com/_NEkwN1SfiXw/TEbyM8XhYKI/AAAAAAAAAOo/WBBPo2viH4I/s800/CarRealistic3.jpeg

I'm rather happy, but I can tell that this is not 100% realistic (I aimed for complete realism).
Specific problems that I can see are the headlight cover glasses and the inside. Those aren't supposed to look so lit up, I didn't intend it to be that way - it just happened. Also they don't look realistic at all.

The windshield has it's problems, but that's the best I could do.

The overall lighting could be better. The HDRI map is a studio environment map, placed on a dome around the car. The car is sitting on a couple of platforms which are supposed to be reflective and metallic, but they aren't.

Well, generally, I would love a few tips and tricks to make this look better.
If there's any info you need to give you insight, I'll be happy to provide.

TinyCerebellum
07-21-2010, 04:16 PM
Hi Hakushinkan,

I think the biggest issue right now is definitely the lighting, which doesn't do your model much justice. The HDR map that you're using looks doesn't seem very well suited for a car render.

The pic below is an example of what a studio setup might look like for a car photo. The softboxes need to be quite large to provide enough light, and also nice reflections over the entire length of the car. I would recommend that you build such an environment yourself, with large area lights that simulate the softboxes. This is, of course, in case you're going for this sort of studio look.

Are you also using a linear workflow?

http://www.andrei-art.com/forums/carStudioLighting.jpg

jtvergarav
07-21-2010, 04:23 PM
Man I think it looks very cool.

Here are some things I would try:

The model is not very clean, specially the front bumper, the edges of those holes. You could try fixing it or downloading a car that's greatly done. Anyway, that's just a detail.

So... I will bother you with the lighting and shading.

I would remove that background, distracts a lot.
Try taking out those lines in the car, just for the sake of testing the car paint.

The car paint. I'd try playing with a standard mia material just to understand how to car paint shader works . There was a guy I used to work with that used presets all the time, including car paint. But when the time to create a slightly complex shader came and there was no preset for it, he could do nothing. Now, don't get me wrong. Presets are great, but in order to understand the core of the shaders it is not a bad exercise to replicate them without the preset (all that shit I said is supposing you are using a car paint shader).

The tires. You can't see them.

and about the lights. Usually when some shader is ****ed up, I start from the basics, and as dark as possible. Then I make it again to realize what's the specific problem.

And make some basic interior shapes to light it, it will help.

Anyway, as I said, I like how it looks. Those are just details.

good luck man

Hakushinkan
07-21-2010, 06:38 PM
Thanks for all the replies :)

About the car paint - it's the car paint shader, yep. But I did a LOT of tweaking on it. I played around a lot, and I'm also familiar with constructing my own combinations now. I'm not very good at it yet, though. I need more experience. As I said, it's only been 2 weeks since the first time I used mental ray EVER. And this was not done with a tutorial, it was done with my own knowledge that I collected from various discussions, experiments, blogs, and some tutorials (none car specific though).

About the model - I'm not going to go back to modeling this at this point. I think I'll just move on to the next project. I learned a lot about modeling from this, and the next one will be better. :)

About the tires - I agree... I'm having a problem getting them to be any good. I just don't know how to make that rubberish look. Plain lambert doesnt do it, I don't know. =\

About the lighting and the studio - I'm going to work on building a studio environment now, based on one of the photos you put up here. Thanks. I'll post another picture when it's done. :)

Oh yes - about linear workflow.
I'm using an exposure simple lens shader, no gamma correction on the render and the only maps that are not gamma corrected are the ones on the turn lights and backlights. I'll go back and correct them but otherwise, everything's fine.

Kyron
07-22-2010, 03:06 AM
Ah I remember doing that Digital Tutors tutorial for that Eclipse in school :), I remember how annoyed I was by using SubDs. Nice that you made the interiors as well, I was too lazy to do that so I just gave it black windows lol :)

I agree with the lighting part. Are you using final gather? If not, it would propably help with some of the bounce lights to light up the darker parts.

If you cant get the HDR images to work right, you can try and map a texture to the environment as well, like a ramp or something, this usually works quite well, especially if youre going for that "studio look".

Hakushinkan
07-22-2010, 09:22 AM
Ah I remember doing that Digital Tutors tutorial for that Eclipse in school :), I remember how annoyed I was by using SubDs. Nice that you made the interiors as well, I was too lazy to do that so I just gave it black windows lol :)

I agree with the lighting part. Are you using final gather? If not, it would propably help with some of the bounce lights to light up the darker parts.

If you cant get the HDR images to work right, you can try and map a texture to the environment as well, like a ramp or something, this usually works quite well, especially if youre going for that "studio look".

Yeah the model is from DT.
I was pretty annoyed with that class because he was very careless when modeling. I had to model it my way, using the class as guidelines. There's much, much more detail in my model than what was intended... But it's a good way to learn :)

Plus I did all the mapping and shading and all by myself. For example I used Mib_Color_mix to do the stripes, instead of the layered shader, because I wanted to use MR materials... which was a pain.

Well for this render I was using irradiance and importons istead of final gather. I think it looks better, more accurate like that.

Either way I need to learn how to light a scene. I cleaned the scene from everything except the car itself, and I just can't get good lighting in there. I've been changing stuff the get a linear workflow, which helped a lot, but it's still very flat and unrealistic.

Is there any guide to how to work with lighting? I think in the end that's the biggest problem with this specific model. The materials work rather well except for some tweaks...

Kyron
07-22-2010, 06:59 PM
I agree with the modelling part, not my favorite tbh. Im terrible at modelling myself and havent found the best way for me yet, aside from good old box modelling. Can you tell me how you got the mib color mix to work with the textures ? I tried using the layered shader as well for another model but as you said it was a pain with MR mats.

As for tutorials on lighting, I suggest you check out some of the DT or Gnomon tuts.

For something like a car, a HDR is a really good start. I don't think you need more than a few lights, and FG turned on, (remember to uncheck primary visibility on the environment so it dosent show up in the render), then you can either make a background in post or create a background with a couple of lofted curves. And then maybe do an AO pass as well.

Gl with the rendering :)

Kyron
07-22-2010, 07:10 PM
Doh... For some reason it double posted :shrug:

Hakushinkan
07-22-2010, 07:11 PM
I agree with the modelling part, not my favorite tbh. Im terrible at modelling myself and havent found the best way for me yet, aside from good old box modelling. Can you tell me how you got the mib color mix to work with the textures ? I tried using the layered shader as well for another model but as you said it was a pain with MR mats.

As for tutorials on lighting, I suggest you check out some of the DT or Gnomon tuts.

For something like a car, a HDR is a really good start. I don't think you need more than a few lights, and FG turned on, (remember to uncheck primary visibility on the environment so it dosent show up in the render), then you can either make a background in post or create a background with a couple of lofted curves. And then maybe do an AO pass as well.

Gl with the rendering :)

Well for a first car model I think it turned out pretty well...
I agree it's not the best, that's why I'm in a rush to get this project done with and move on to a new work, which will be better.

About the color mix:
It's a bit complicated but once you understand the principle, it's fine.
Basically you need to understand that the "weight" parameter controls the strength of the layer, and that the color is the layer itself. Then there's the parameter that controls how many layers it'll compute.

On this case, I had to have the car paint as the bottom most shader, so I put that on "color 0". Then, I needed to have everything on the layer on top of that transparent, except for the stripe part - so I connected an alpha texture map (not a material, just a texture map) with the right UVs on the weight parameter of Color 1. Then, I put the color of the stripes (either textured material, or just a colored material, any one you like) on the color channel of Color 1.

Then I connected the color mix to the material shader of the blinn that holds my stripe texture itself, and the blinn went on the car. Pretty simple once you get the mechanism, but man, when that's more or less the first thing you do in mental ray, you can go bald from it.

Kyron
07-22-2010, 07:14 PM
Going bald from Maya happens on a regular basis for a lot of people I think :D

As for the car model itself, I think its modelled fine. If you just want to practice lighting, you don't need to model a new one (unless you want to ofc) :).
But you continue lighting your current model, it looks like youre half the way anyway.

Hakushinkan
07-22-2010, 07:19 PM
I just don't know what else to do. I'm kinda stuck. I have all the knowledge, but I just don't know what to do next to make it all look better. (well, not all the knowledge. I guess I have some though :X)

It keeps looking like it's not lit enough, or lit too much, or not glossy enough...
The windshield looks bad, the headlight covers look bad, etc.
I keep trying to get everything to look nice, but nothing beats a good old tutorial to open up your mind to new possibilities.

If these programs worked more in sync with real world logic it'd be awesome. But it's like I have to learn a whole new set of rules to imitate a different set of rules, which I already understand. :X

InfernalDarkness
07-22-2010, 07:43 PM
I think the key component you're missing is indirect lighting. It's a beautiful car, one of my personal favorites as well, but looking at it on 3 different monitors there's a distinct lack of FG interaction and also indirect light inside the Eclipse. Are you using Final Gather?

I'd lose the HDR and try a more direct lighting approach. Make your scene just like the Mercedes example, using Area Lights and Portal Lights, and a few spotlights in key places to give extra highlights.

Your glass Windshield shader needs to be much thicker too. Did you model the glass as one panel, or does it have two sides? Makes sure you have a glass piece for the outside and one for the inside.... Gotta have two. You can merge them after modeling, but having two will give you that thickness.

Hakushinkan
07-22-2010, 08:35 PM
I think the key component you're missing is indirect lighting. It's a beautiful car, one of my personal favorites as well, but looking at it on 3 different monitors there's a distinct lack of FG interaction and also indirect light inside the Eclipse. Are you using Final Gather?

I'd lose the HDR and try a more direct lighting approach. Make your scene just like the Mercedes example, using Area Lights and Portal Lights, and a few spotlights in key places to give extra highlights.

Your glass Windshield shader needs to be much thicker too. Did you model the glass as one panel, or does it have two sides? Makes sure you have a glass piece for the outside and one for the inside.... Gotta have two. You can merge them after modeling, but having two will give you that thickness.

Thanks for reminding me about the windshield. I totally forgot that during the modeling process I told myself to double that glass layer, and probably forgot.

And yes, I am using final gather... This specific render was with irradiance and importons, and it was the best one I done yet...

I'm working on a new render and I'm trying to use all the suggestions I got here. I hope it'll be any good.

Hakushinkan
07-25-2010, 06:08 PM
Here's what I'm with now:

http://lh3.ggpht.com/_NEkwN1SfiXw/TExvJrDIXgI/AAAAAAAAAPY/VwPb2gtk0gg/s1152/FinalCarRender.jpg

What I basically did:
I used the advanced shaders to put this car into the background.
It sits on a matteshadow surface, and I used the rayswitch environment to give it reflections and a background image.

I feel like the car is not illuminated enough, but when I add a spotlight to the scene, I get these weird black aliased artifacts all over the sides of the diffused areas.

Any thoughts of why it happens?

A better (in my opinion) version:
http://lh4.ggpht.com/_NEkwN1SfiXw/TEy5nKc3yYI/AAAAAAAAAPg/g_ulDwYXvGo/s1152/FinalCarRender.jpg

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