This exercise has reminded me of just how many components you need to get right for a render to look photo-realistic. An image is only as strong as its weakest link and a technically brilliant render can be a failure if it is framed badly, has depth of field that is un-natural, or burnt out highlights. I love this quote from Jeremy Birn, author of the slightly dated but surprisingly still helpful ‘digital lighting and rendering’ – ‘If it smells like fish, it is not good fish…if it looks like computer graphics, it is not good computer graphics’ (2000)
Every texture and model has to be right, because it only takes one CG looking texture or piece of faceted geometry to remove believability from the whole project.
Mental ray makes things a little easier if you know the rules of sticking to a physically accurate workflow. Sticking to quadratic decay on lights and using colour management takes a lot of the guess work out of the rendering workflow so you can think more about artistic solutions.
I managed to stick to a colour managed pipeline except in times when I was selecting swatch colours based on render feedback, I did not see the point in using gamma correction nodes in these particular cases. An example of this is the case of selecting swatches for SSS colours or the granite cell colours. As I was adjusting colours based on render test feedback, it seemed counter productive to then go and work out the gamma corrected colour.
I learned a lot about the render settings and what you can get away with to make render times faster.
I am really happy that I had problems with long render times due to mental ray lens shaders – it forced me to learn about the quicker option of rendering a camera depth channel and applying lens blur in post. I had never done this before. There are limitations of course and I found that I could only push the blurs so far but it seemed to fit my requirements.
I also really like the approximation editor, it worked like a dream for tesselating the branches on the grapes with a single click.
Final gather was my ‘go to’ choice for indirect illumination because of it’s ease of use ‘the simplest method of providing illuminition in your scene’ (2010)
As far as the texturing side of things, I REALLY like the mudbox-photoshop-maya-mental ray pipeline.
This kind of pipeline is explained by Owen Demers in ‘Digital texturing and painting’ and the benefits (over just photography alone) are can summarized like this-
• flexibiliy of modification
• you can build your artistic eye and gain confidence
• not becoming a slave to photographing something every time you want to build a texture
I enjoyed using the freedom of photoshops transformation tools to manipulate bits of photos so they could be re-used as stamps. Mike Hill related this process to how we as 3D modellers manipulate geometry with deformers ‘many of you will take some basic geometry and play with modifiers such as stretch, taper bend twist and spherize to generate something original. It is the same principle in photoshop.’ (Sykut & Ragonha 2011,p10)
Apart from wishing I had more time to paint in mudbox to truly get the textures perfect, I really only had 2 problems along the texturing road.
1/ Initially I had a terrible time trying to get alpha working on my own custom stamps. It was only when I realized that your custom stamps have to be painted white in photoshop rather than black that I mastered the pipeline. By this time I had already done quite alot of texture building using the default brushes which also worked quite well but I made sure I re-did the apple and banana with my own custom stamps to make sure I had a handle on it.
The other area where I had a bit of trouble was using normal maps. I hand sculpted detail for the orange in mudbox, extracted a normal map for use in maya. This worked brilliantly until I mapped a hand painted diffuse colour. The combination of the normal map and diffuse produced a highly visible seam on the UV cut which I could not seem to get rid of. I was running out of time to find a fix for the problem so I had 2 easy options-
a/ rotate the geometry so the seam was not visible in the frame or
b/ not use a diffuse colour map
I went for option b because the orange looked really good anyway just using a flat orange swatch and letting the normal map do all the work!
Mostly I found this whole process really relaxing and enjoyable and it has contributed to me seriously thinking about pushing to do rendering 2 and maybe even eventually trying to build a career in texturing, rendering. I am already pretty interested in compositing and I think it might make good triple skillset.
I think I would do more polishing before showing off the fruitbowl in a showreel but I am quite happy with what I achieved given the inevitable time pressure of learning some of the necessary techniques very late in the semester.
Demers, O 2002, Digital texturing and painting, New Riders, USA
Sykut, A & Ragonha M 2011, Photoshop for 3D artists, 3D total publishing, UK
Birn, J 2000, Digital lighting and rendering, New Riders, USA
O’Connor, J 2010, Mastering Mental Ray: Rendering techniques for 3D and CAD professionals, Wiley, Indianna USA