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Pixelmech
03-03-2007, 04:23 PM
Hi there,

Been working on this project for a while, my first model and render. It was suggested I use physical sky/sun with FG, which is included in v6. So I am, I have HDR in the car paint and also as an environment shader. Any ideas on improving this? I have no idea how to fix that bad patch on the right side of the door either. I can show render trees for whatever material if you want to see them.

http://www.pixelmech.com/rev/zrender34.jpg

CiaranM
03-03-2007, 06:35 PM
I think right now the image looks very flat as a whole.
I think you should let the fancy physical sky etc. take a back seat for the moment and try to get a good lighting setup with regular lights first. You need a stronger light source to give the image some depth, perhaps use an distant area light (not too large) coming from slightly to the right of the image. Perhaps lower in the sky with a very slight orange tint. This will allow the car to cast some strong shadows, which will help it to stand out from its background. You should make the area light visible so that the car picks up its reflections.
You'll need a fill light to represent the blue of the sky. This could be done classicaly using a blueish directional light, no shadow casting, with perhaps 40% intensity of the main light. Experiment.
Feel free to add more lighting on the car if you feel it necessary. Imagine a real photo shoot, they would rarely rely solely on lighting from the sun. Do you have any global ambience enabled? (check under the render menu). If so, turn it off! You can bring some back later if need be.
Your car doesn't have any contact shadows with the ground, which gives the impression that it is floating. The area sun light will help with this, but you might also want to add an ambient occluion pass to add some nice detailed shadowing. There should be instructions in the manual on how to create this pass.
I really don't like your HDR environment reflections. First of all I think they are too strong, especially on the winscreen and front of the car. Secondly, it looks like a pretty low quality image. Search around for a higher quality image.
You also need a higher quality texture for the road surface. Do have bump mapping on the road? You should. Don't be affraid to paint a texture if you can't find a decent photo.
Remember, your car is the focus of the peice, but right now it just doesn't stand out from the background. There's no harm in using FG etc. for this image, but for the moment I just don't think it is working. It's just too ambient, with no direction to the lighting. Experiment with regular lighting until you find a look you like, then expand from there with more advanced techniques. Also think about the composition of the image. Why should my eye focus on the car? It's being drawn to the background, which if far too close and distracting. Check out some car advertisements and learn from the dramatic lighting and compositions they use.

As for the weird texture on the back wall, I suspect it may be a uv mapping problem. Check your uvs to see if there are any overlapping polygons. They should appear red in the XSI texture editor.

It's a fine start, I'm sure you'll be able to make this look really great, with a bit of work.
:thumbsup:

Pixelmech
03-03-2007, 07:54 PM
Thanks for taking the time to respond, I appreciate it. Ok, so I have been back and forth between image based and studio lighting setups at least 3 times based on suggestions :) I will save a copy and try your suggestions though. I do have some questions.

1) What do you do for a backlight when the car is close to the building? There seems to be no place to put one.

2) When I click on ambience in the render menu, it allows me to change the color, but there is no way to turn it off per se - do you mean set it to black?

3) I read in the manual how to create a separate pass - in fact I made a grayscale pass to just see the lighting, not a problem. However, it doesn't say how to make it an AO pass. Do you have any links or tutes for that?

4) I can search around for a better HDR, I agree on the windshield it is too much. I think part of that is the problem with my glass shader which is awful.

5) I've really struggled with the road surface. That one is finally the one I found that I like. I can't seem to find anything else higher res. If I were to paint one, how high of a resolution should it be? I am using bump on it, although on that render, above I think I did it wrong. I had enable bump mapping enabled on the bump map generator node, but not the image node. It's confusing that you have that setting on BOTH items - do they both need to be enabled? If they are, which setting takes priority?

6) Agree the composition is not super strong. In essence, this is my first project that was simply a practice ground to get up to speed in XSI as quickly as possible. I don't want to spend too much time modeling anything else or messing with scene elements too much beyond that, so I think for the time being I will stick with these scene elements, although if you have some positioning ideas that might make it better, I could shift things around.

7) You are right about the UV problem on that patch - this is what I see, but I can't figure out how to fix it - the two pieces share the same point apparently, how can I fix that?

http://www.pixelmech.com/rev/uvproblem.jpg

Again, thank you for the comments, it's very helpful. I'll start on an alternate version of this with the lighting you suggested.

Tom

Rens
03-05-2007, 11:34 PM
I hope Ciaran doesn't mind me answering these for you (good comments there btw). I'm using v5.

1) I didn't see a back light mentioned, just a big fill for the sky and a directional for the sun. Your wall could kind of act as a back light in this case.

2) Black = Off.

3) One way is to make a new pass and assign an AO material directly to your obj partition. This will override any existing materials on those objects.

4) For a glass shader try T2S_illumination or L_Glass. Links can be found here, xsi-base or google.
EDIT: Oh hey, just noticed the thread below this one:
http://forums.cgsociety.org/showthread.php?f=24&t=470038

5) As for your map size, basically match it up with the final render size so you get at least one pixel of map size for every pixel of frame size. If your road is a grid which ends just outside of the frame then a 1000x1000px map should do, assuming you render at 720px.
Only enabling Bump Gen will do. Don't know which on has priority, but you can easily check that yourself

7) Two things that should work:
- Select polygon mode in the UV editor, deselect island selection. Select the messed up polygon in the editor and then move it. Now you can select the vert and weld it where it should be.
- Or, select the two verts, go to the viewport and deselect the vert that doesn't need moving. Back in the UV ed move the still selected vert to its position.

Good luck,
R

Pixelmech
03-06-2007, 12:11 AM
Thanks for answering. I'm rendering a beauty pass now and I think I figured out the AO pass. What would be the best way to composite the two in PhotoShop? Multiply?

I had the vertex fixed on the wall but it keeps snapping back, I may have to retexture that. I installed the l_glass in my workgroup but I can't figure out how to access it. I'll post a render when its finished

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