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SanguineJackal
05-07-2010, 02:23 AM
Hey all,

I've got my final project due here in about a week and I have some very basic lighting and lightlinking done. Just a directional yellow light and a directional blue, with a sphere surrounding the scene. I need to make it look like the reference painting ( http://coolvibe.com/wp-content/uploads/2010/02/city.jpg ) and am thinking about using some ramp shading for it?

This is the first render of what I have, with no Raytrace or Emit Photons:
http://img.photobucket.com/albums/v355/Sekhimet/Render1.jpg

And the other one, with both the aforementioned options turned on:
http://img.photobucket.com/albums/v355/Sekhimet/Render2.jpg

Any ideas would be greatly appreciated. :) I am thinking of taking this into Shake afterward for some compositing, but the teacher would like as much of it done in Maya as possible.

playmesumch00ns
05-07-2010, 06:35 AM
Assuming you're using mental ray, use the physical sun/sky or find yourself a good hdri as a starting point.

The two things I notice most about the reference image are 1) it's pretty overexposed and 2) it's very hazy.

SanguineJackal
05-07-2010, 07:34 AM
Assuming you're using mental ray, use the physical sun/sky or find yourself a good hdri as a starting point.

The two things I notice most about the reference image are 1) it's pretty overexposed and 2) it's very hazy.

I actually did use physical sun/sky at first but she said she didn't want us to do that for some reason... probably just trying to get us to work with limitations? ( http://img.photobucket.com/albums/v355/Sekhimet/Render_Scene_Mockup.jpg )

For the overexposure, I could probably just change the intensity of the lights themselves, right?

For the haze... I saw someone in a tutorial use a Ramp shader for it. Would that be useful in this, do you think?

playmesumch00ns
05-07-2010, 08:53 AM
I assume "she" is your tutor? OK if she wants you to do it old-school I'd build a light dome using one of the many free tools on teh interwebs for the sky contribution (it would help if you could use an hdri to guide the light placement so you have some directionality in the dome rather than just having a boring ambient occlusion look), then use a warm directional light for the sun. the shadows in the reference image are pretty soft which will be key to achieving the look you're after.

I'd render the dome and the sun as separate images so you can rebalance in comp to get the right colour and exposure to match the reference.

For the atmosphere, you could just do a fog-type-thing based on the depth pass in comp, but it would be better to do a render with a proper atmosphere shader that could take into account shadows from your sun light. if you render this as a separate pass as well (putting a black surface shader on the buildings) you'll be able to just add it onto the main render in comp and tweak to your heart's content.

Also pay careful attention to the lens you're using and the placement of the buildings in your scene to get the composition right. Currently your images look very flat compared to the reference.

For a finishing touch put a subtle bit of bloom onto the image and give a slight chromatic abberation effect to simulate a real lens. Just make sure to make this subtle (I mean so subtle you can't really tell it's there).

EDIT: oh and I wouldn't bother to use photons for something like this: just do a final gather pass on it once you're happy wth the lighting, but you should be able to get a nice-looking image with just the techniques I've described above, the FG will just add that extra bit of niceness.

Reed5point0
05-07-2010, 02:16 PM
Without using the sky I can think of a few easy ways.

If you are allowed to use render passes, I would suggest rendering a Z-Depth pass and using the alpha/greyscale image it outputs to drive a Depth of Field type effect.

If you cannot use render passes and just composite the effect, I would setup the render camera to do the Depth of Field.

Haze can be done using environment fog.

The Highway thing below in your image is waaaaaay to dark. The first goal for you should be matching the colors / general lighting. Everything is also too vibrant, the ref image is pretty saturated/overexposed like everyone else is saying.

The back buildings could get that blown out look they have by increasing the light intensity, but also look into the Mental Ray Exposure node and your camera settings as well.

Don't forget you can use the light linker to control lights on a per building basis...

An Occlusion Pass in the end would help with the shading, and you said you had raytracing and GI...but what about Final Gather? Hell I just started playing with Importons / Irradiance Particles, and love em.

SanguineJackal
05-07-2010, 05:50 PM
To be perfectly honest... she said we can use composition, passes, pretty much anything we want EXCEPT physical sun/sky. She also said she would much rather we get everything as close as possible in Maya, because this is a Maya class, not the Shake or Nuke class.

She has not taught us to render in passes, to do environment fog, or particle modeling at all (said that would need a separate class).

I am using Final Gathering in MR, rather than Global Illumination. It just seems so much better!

Light linking is, by the way, my new favorite toy. It is helping IMMENSELY. Now that I look at it, it seems that I forgot to link the highway to the lights, because I was so focused on getting the buildings right! :x

Currently there is a sphere on there, the inside of which is mapped with a timelapse day-to-night scene I had to put together in Photoshop. There are more directional lights (currently hidden, because they weren't ready for a render yet) that are parented under this dome. The idea is that, as my animation makes the transition from day to night, the dome will rotate along with the light sources attached to it. Since only a tiny amount of sky is visible, the treeline that is still showing up on the model isn't visible to the camera.

This is the tutorial I have been trying to base much of my workflow on. (http://www.the-area.com/tutorials/rendering_in_layers_in_maya ) When I showed it to my professor, she said it would be fine but hinted that I could make it better- and get a better grade- if I got as close as possible in Maya, because she is going to compare the Maya scene and the composition to the reference image.

If anyone has a link to a tutorial for any of the aforementioned issues I'd greatly appreciate it. :)

SanguineJackal
05-14-2010, 12:30 AM
Okay...

I have a "final" render for the day part of the scene. I did an ambient occlusion render, then one with the lighting, and basically Photoshopped them together.

http://img.photobucket.com/albums/v355/Sekhimet/Ambient_Occlusion_Pass.jpg
http://img.photobucket.com/albums/v355/Sekhimet/Color_Pass.jpg
http://img.photobucket.com/albums/v355/Sekhimet/Final_Pass.jpg

But in regards to the reference image....
http://coolvibe.com/wp-content/uploads/2010/02/city.jpg

It doesn't look as good. The back buildings are just too washed-out, I'm not sure what else to do. I took down the intensity of the linked lights... it's really getting on my nerves. She wants this in by Sunday.... said as long as I can get this to look right, I don't even have to bother with the night scene (though I am thinking of going for that too... maybe...)

I uploaded the project folder to RapidShare... if anyone has any suggestions or would like to take a look, I'm very interested to hear what you have to say. :) Thanks!

http://rapidshare.com/files/387043842/samanthaFullen_Project2_Building.zip.html
(Not sure what the MD5 is but in case it's needed: 00A69CE9FA34FDD18734CBA5BD383B28 )

playmesumch00ns
05-14-2010, 11:51 AM
OK well it looks crappy because your lighting's crappy.

First though spend some time working on the composition. Hide whatever fill lights you've got and just render using the key light, placing the buildings to better match the reference image. Notice how you can't really see to the background in the reference while in yours there's a fairly big hole which shows clearly that your city's only a couple of buildings deep.

Tweak the angle of the key and the position of the buildings to match the shadows you see in the reference. Notice the long shadows being cast on the buildings to the rear of the reference, and how the second building on the right is almost completely in shadow. These give the picture interest and depth and will be vital to achieving the right look. You might want to place some cylinders off camera to cast shadows to achieve these.

Once you're happy with the key light, then look at the fill. I'd *highly* recommend using IBL for the fill lighting as this will give you much more interesting form. Just find a generic sky hdri on the internet. Please, please, please don't use ambient occlusion. It's ugly as sin and will just make your image flat and grey.

Render the key light and the ibl individually without FG to see what they're doing. Once you're happy with the shadowing and light distribution of each bring them into ps or a compositing program and add them together, to tweak the relative brightness and colour balance. Your lighting is way off in terms of key/fill ratio particuarly. Look how deep and blue the shadows are in the reference, and how warm the key light is. This is essential for the character of the piece. Once you're happy with the look of the image in ps, bring those changes back into your 3d app for the final render. Only turn FG on when you're happy with the base lighting.

Oh and you might want to smooth the buildings out a bit to kill some of the faceting.

SanguineJackal
05-14-2010, 01:43 PM
OK well it looks crappy because your lighting's crappy.

Ouch. Okay, thank you. :P

First though spend some time working on the composition. Hide whatever fill lights you've got and just render using the key light, placing the buildings to better match the reference image. Notice how you can't really see to the background in the reference while in yours there's a fairly big hole which shows clearly that your city's only a couple of buildings deep. I have spent SO much time trying to get the positioning right it is ridiculous. That building in the very back is a lot of the problem; if I move it over even just a bit to cover up the big patch of blue, you can see it... well... eating the highway. I will tinker with it a bit more though and see what I get. I was trying to use the Ambient Occlusion to give it some semblence of depth, because the render of just the lights was... god-awful.

Tweak the angle of the key and the position of the buildings to match the shadows you see in the reference. Notice the long shadows being cast on the buildings to the rear of the reference, and how the second building on the right is almost completely in shadow. These give the picture interest and depth and will be vital to achieving the right look. You might want to place some cylinders off camera to cast shadows to achieve these. Woah, good idea! I hadn't thought of that for whatever reason. I just spent forever trying to make the darn shadows look right but... well, you see how it turned out. :P

Once you're happy with the key light, then look at the fill. I'd *highly* recommend using IBL for the fill lighting as this will give you much more interesting form. Just find a generic sky hdri on the internet. Please, please, please don't use ambient occlusion. It's ugly as sin and will just make your image flat and grey. I am new to IBL, so I looked up a tutorial for it. (http://cg.tutsplus.com/tutorials/autodesk-maya/an-introduction-to-ibl-and-ao-using-3delight-in-maya/)The tutorial is using .tbl files for the envmaps. It's also using a thing called 3Delight, something I have never heard of but will have to give a go... looks like a Maya plugin, downloading it now. Also, right now my background (mapped onto that sorry dome) was a bunch of HD sky images I Photoshopped together so that in order to progress from day to night, I just had to rotate it. But, I want to get all the lighting for this scene done right first...

Render the key light and the ibl individually without FG to see what they're doing. Once you're happy with the shadowing and light distribution of each bring them into ps or a compositing program and add them together, to tweak the relative brightness and colour balance. Your lighting is way off in terms of key/fill ratio particuarly. Look how deep and blue the shadows are in the reference, and how warm the key light is. This is essential for the character of the piece. Once you're happy with the look of the image in ps, bring those changes back into your 3d app for the final render. Only turn FG on when you're happy with the base lighting. I'm gonna take a wild guess that FG is going to bog down my render time. Until then, should I use Maya software on the rendering or keep it on mental ray? You can probably tell but this is the first scene I've ever had to light and render. I'll have to try some tweaking on the lights when I get home from work tonight.

Oh and you might want to smooth the buildings out a bit to kill some of the faceting. There's faceting going on? The buildings are smoothed out, she made us bevel the crap out of our models before we ever started the lighting so that we could smooth them. But the way the shadows look in the "final" image, it does make it look very... icky.

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