Making Of 'Urban Environment'
After collecting a good amount of photographed reference material, I go to work on making them into usable textures. If correct lighting & perspectives are going to be used, then it should just be a case of tweaking them into position. These photos need to be taken on overcast days to avoid shadows or obvious light sources.
The photo reference is taken with a 10MegaPixel camera at a resolution of 3888x2592, these are then scaled & cropped down to 2048x2048. In Photoshop I use the distort tool to push them into shape, laying down a grid can ensure your lines are parallel to each other.
The buildings start as single polygon planes, which are UV mapped & have the final texture already applied, I slowly make cut's & extrusions following the underlying texture as a guide. A recent feature in 3dsmax is the 'Preserve UV's' option, when checking this you can easily move points & edges around without affecting the underlying UV's. Because the mesh is under constant change at this stage, it may require some remapping (the preserve UV's feature wont work all the time) wherever possible I use planar projections. For the sides of the extruded windows, I have given a generic Unwrap UVW & placed on the UV template to take best advantage of the texture. Any extrusions & bevels will quickly destroy the UV mapping.
Use the texture as a background in the UV editor to get even better control in matching your model to the texture.
Many smaller props are made to fill out the scene, it's the small details like these that make a scene interesting to look at. You might not notice them when first viewing the full image, but you would notice if they weren't there. I also make use of assets I've modeled in the past.
Before working on the final lighting, I set up the composition, using the perspective viewport to position the view then using ctrl-c to create a camera from that view. For environment renders, I find a lower focal range helps to create a sense of depth to the scene, this one uses a lens of 31mm. I then usually put a slight tilt on the camera to add a bit of drama to the composition.
Lighting is kept as simple as possible, I've used a finalRender GI solution with a direct light casting raytraced shadows. The shadow strength is around 80% & the light Strength is 120%, as I'm rendering in passes this.
The render time took 4 hours at a resolution of 4096 wide, with the total polycount was around 300,000. The interiors of the buildings are modeled with very simple boxes, just enough so when you look in a window you'll see at least a wall or two. The distant buildings were rendered separately.
Composition / Post work
I regard the renders as merely a starting point to further, fine tuning of the image in Photoshop, so multi-pass rendering is essential ('Render Elements' in 3dsmax). Z-Depth is great for selecting background areas & applying atmospheric effects. Shadows & light can more easily be controlled if it's on a separate layer etc, I also made several Matte passes of various objects to make selections in Photoshop easier (a matte pass creates a mask of an object or selection of objects). I do a fair amount of colour correction & painting light rays & atmosphere and the specularity pass is good for picking out some highlights. The specular pass is also duplicated several times & set to screen, the occlusion pass is set to multiply. The opacity of all the layers is adjusted.
Working with passes is very specific to each image & what works for one may not work for another.