PRMan RMS 18: Some tips on Rendering in Maya

RMS 19 is around the corner and will be released this fall. The new RIS engine works different than the RMS 18 reyes and ray tracer hiders but these old hiders will still be available. So why not write an article on how to get decent quality images out and how to streamline your workflow. Some of the workflow tips will still be useful in RMS 19.

What are my render options while working on a scene?

There are three ways to get your previews rendered. You can use the internal renderer. The interactive re-render option or the PRMan external renderer.

• The internal renderer: Works just like the Maya renderer or Mental Ray. My biggest problem with this method is that Maya becomes unresponsive while rendering. You can stop the render process by pressing Esc but you can't modify any parameters in Maya. You can only twiddle your thumbs while waiting.
• The re-render option: In this mode the renderer will constantly update the image while Maya stays responsive. You can change settings on the fly and see them change in de Render View. I have seen people using it successfully. Personally speaking I do not have a great experience with it. It does sometimes freeze Maya as it is still a process within Maya. This can really disrupt the workflow. It works best when you output your image to "it" and not to the render view in Maya.
• The PRMan external renderer: In this mode the scene gets exported en queued up in the Local Queue manager (or the farm if you have one) and then rendered by RenderMan Pro Server. The big benefit is that it is an external process which won't block Maya from being used once the scene is launched. It is slightly less interactive than the re-render mode but is very stable. Since it uses the Local Queue it is possible to queue up multiple renders. It also uses "it" which is superior image viewer compared to the Render View.

How to speed up your workflow by using the external renderer

RMS 18 has two modes of rendering: reyes or ray trace. Reyes is a hybrid renderer (used to be scan line only) and the other mode is of course a full ray tracer. They both produce excellent results but they respond slightly different to the quality settings. I have made a test scene with a pencil and three black spheres lit with an HDR map.

Let's have a look at those settings (click on the images to see a full res version):

Image1: RenderMan Globals: Quality tab and advanced tab. (click image to see full res).

Under the advanced tab you can choose your render mode (or also called hider) (right window on image 1). When choosing reyes there is not much else to set in the hider tab. When choosing ray trace it is possible to tweak some settings. I prefer the adaptive path tracer. When you check incremental the image will start rendering noisy but will improve over time. I really like this as you get immediate results but you can also wait for more details to show up while it continues calculating the image. It allows you to judge the image quickly so you can start making tweaks. The image keeps rendering while you make those shading tweaks in Maya or when updating texture maps. (but does not incorporate them until the next render). For me it means I can do two things at once.

Image 2: RenderMan Render Options

To set up you external renderer you need to adjust some setting in the RenderMan Render Options.

• Check the external renderer and choose "it" as your image display or your image viewer.
• Choose local queue and local render (unless you have a complete render farm at your finger tips).
• Set the environment key to "rms-18.0-maya-2015 prman-18.0". Important: You do need to have the RenderMan Pro server installed for this to work.

How to simply adjust quality.

The next section shows some differences in quality. Make sure to click the images to see the actual differences between them. The blurred reflection on the spheres and the text on the pencil are good places to look.

Reyes is easily controllable with the shading rate setting (left window on the image 1). Large values will produce course quality but will render very fast. A shading rate of 5 will give very quick renders but your texture maps will look blurred. This can be enough to see if everything renders but isn't very great to check the detail in your maps while you are painting them. The letters on the pencil are unreadable. Check out the test image below (Image 3):

Image 3: Reyes: shading rate 5, pixel samples 3x3

When you lower the shading rate, the quality will improve. Production renders are always on a shading rate of 1 or lower (like 0.5). This will increase rendering time. On the next image (Image 4) I lowered the shading rate to 0.1 which makes the small letters on the pencil very readable but the render time was 7 times as high as shading rate 5.

Image 4: Reyes: shading rate 0.1, pixel samples 3x3

The quality controls work a bit different when you are using the ray tracer. In general you can leave the shading rate on 1. It is in fact the pixel samples which control the quality of the image (check right window on Image 1). You can see on the next image (Image 5) that the ray tracer shows the texture maps more clearly but has more problems with noise and anti-aliassing. It is very noticeable in the blurred reflections.

Image 5: Ray trace: shading rate 1, pixel samples 2x2

Increasing the pixel samples will render better quality but will increase render times exponentially. On the next image (Image 6) we can see that 4x4 pixel samples is enough for a still image without depth of field. It is very comparable to the high quality reyes image.Once you start adding movement or shallow depth of field it needs much more samples to get rid of the noisiness.

Image 6: Ray trace: shading rate 1: pixel samples 4x4

Conclusion

As you can see, both the good old reyes and the newer ray tracer produce excellent results. I tend to lean to the ray tracer as I like the incremental path tracer. It is just great so your image improve over time. It is a bit slower than reyes though but delivers very sharp images  when the pixel samples are set correctly.

Getting into the VFX business

Every now and then I get the question on how to get into the VFX business. In this post I'll give some pointers which can help you to get on your way. I have to warn you though. It is not an easy business to get into and a tough one to stay in. The competition can be quite stiff. Although I do not encourage working many extra hours you probably will at some point as you have to meet deadlines. In practice it is never a nine to five job. If you do not have a passion for computer graphics it might be better for you to find another occupation.

Now that I have warned you, let's go over the pointers.

Education

In the old days CGI was so new that no courses on the subject existed. It was something you had to learn on the job. Since it involved computers it was helpful to get a degree in computer science first but it wasn't always necessary. Many people started in VFX companies at the bottom of the ladder as runners and were allowed to train on the expensive workstations during the evening. If you were good it was possible to get promoted from runner to a junior position in the company. Usually this was in the tracking or rotoscoping department.

In the last decade it has all changed. Software has become more user friendly and you don't need to know how to program any more. Artistic people belong in this business as much as the tech heads. It can be done on mainstream hardware and many software packages have learning editions out there which allow you to get first hand experience for a small amount of money or sometimes even for free.

As in many things it is always smart to get some education first. When I started there were no VFX courses in Belgium at all so I had to move to the UK for an education. Today, your local school may have a computer animation course or you might try online courses like the ones available at FXPHD. Keep in mind that just learning how to work with Maya or any other software package is not good enough. I really recommend that you learn about traditional film making too. Learning about cinematography and story telling is a huge added value to your knowledge and will make your work so much better.

Practice

I can't stress this enough: practice, practice, practice... till it makes perfect. Nobody can model a perfect human model from day one nor paint a beautiful matte painting when opening Photoshop for the first time. Everyone needs to practice, even the super talented people. It is only by doing so that you learn it. You need to constantly hone your skills. Learn to understand why something is good and why something is crap. Get others to look at your work and let them comment on it. Learn from the advice which more experienced people give you and then go back to practicing. Reading about it and watching tutorials is great but if you do not practice it doesn't help you all that much.

This seems like a lot of hard work and it is. I spent many late nights on trying things out and practicing my skills while I was a student. Don't get disheartened when your progress is slow. Some things take a while to learn.


Once you start working you will have less time to practice and it can become harder to pick up and train new skills.

Generalist vs Specialist.

It really depends in what kind of industry you will work in when thinking about becoming an generalist or a specialist. Being a jack of all trades and a master of none can be really beneficial in a small company or when making VFX for commercials. You probably get many small projects each year and usually the teams are small too. It is even possible that you have to do the entire job on your own which means you got to model, animate, shade, light, render and composite it all yourself.


When you are aiming to become a VFX artist in the film industry it is very likely that you will have to specialize in certain skills as it demands high quality. This means you will be much better trained in your particluar field and therefor produce better and faster results. It also means that other skills will be neglected and you will probably never become good at them.


I do recommend to go over every category and at least try them a couple of times. This way you can see what you like most and you will understand the whole VFX pipeline.

Portfolio and Showreel

When you go to apply for a job make sure to have a portfolio (for Matte painters and concept artists) or/and a showreel which showcases your best work. Nobody will give you a job when you can't show the work you have produced in the past. It is even more important than your CV.


Only show your best work. One bad shot on your reel will pull the quality of the whole reel down. Don't make a ten minute reel. Nobody will watch that as most recruiters do not have time to do so. Two minutes is more than enough. If you don't impress them in those first two minutes of your reel you probably never will.


Focus your reel on the job you are applying for. If you want to be animator show animation. If you want to become a lighting TD show finished shots with a breakdown on how it is done and so on.

Conclusion

I don't want to discourage anyone but VFX is much more hard work than glory. If you are really passionate about VFX it can become a very rewarding job but keep in mind it is a tough job.

Now go practice some more.