Page 1 of 1

Another question regarding quality of render

Posted: Sat Nov 29, 2014 10:59 pm
by prosthotoothist
I have not found an answer to my question, so I am asking the following: what is the best approach to get a really high resolution render. My situation is this: I am working on projects that will be used in the teaching of dental students. My renderings will be projected in a classroom using an HD projector which has a resolution of 1366 X 768. The images will be projected onto a very large screen, so any lack of sharp detail will be glaringly obvious. I have tried several test Maxwell renders using the native resolution of the projector as well as double and quadruple resolutions to see if there is any improvement of the "jaggies" around objects. I have used an SL up to 20 and did one render for 4 hours. I have not seen much of a difference from one image to another, so I am needing some advice as to what approach will get me the highest resolution images without taking the rest of my life to complete. I plan to import my final renders (some will be animations) into Avid Media Composer for editing into the final presentation form.

Another question that I should probably ask is whether I am expecting too much high resolution detail without investing many hours (or days) for each render. I see examples of fantastic renderings from others and think "boy that is great" and am disappointed when mine don't turn out well at all. Since I am retired from teaching, I have the time to try almost anything to see what might work better. In fact, over a period of the last couple of years, I have tried many of the other rendering engines and am now trying to get Maxwell to work for me. So far, I have been "underwhelmed" by almost all of the renderers available in 3ds Max 2013. Please be totally honest about my expectations since I am really in need of expert guidance.

Any suggestions will be greatly appreciated.

Thanks,

Tom

Re: Another question regarding quality of render

Posted: Mon Dec 01, 2014 10:33 am
by Mihnea Balta
The the resolution of the projector is 1366 X 768, you should render at 1366 X 768. Rendering at a higher resolution will not make any difference because the display system will just downscale it. Sometimes people render at a higher resolution and downscale so that noise or jagged edges are averaged out by the downscaling filter, but the higher resolution will mean longer render times, and you will probably get the same quality if you simply let the render run longer at the original resolution.

Maxwell has high-quality antialiasing which is always on, so you shouldn't get jagged edges. Maybe you get blurriness from depth of field or just noise. It is difficult to say what the problem in your case is if you don't post some images to exemplify it.

Also, this does not sound like a plug-in specific problem, so I'll move the thread in the main forum, where you're more likely to get help with image quality issues.

Re: Another question regarding quality of render

Posted: Mon Dec 01, 2014 2:07 pm
by Mihai
Post some renders please. Much easier to give advice that way. Maxwell is the last render engine that should have problems with aliasing.

Re: Another question regarding quality of render

Posted: Mon Dec 01, 2014 2:13 pm
by tom

Re: Another question regarding quality of render

Posted: Mon Dec 01, 2014 2:20 pm
by choo-chee
I would suggest rendering at twice the resolution for the plain simple (from my experience) that many times during presentations, people ask you to zoom in... and that's where you do want to start mumbling something about "resolution" "render time" etc....

Re: Another question regarding quality of render

Posted: Mon Dec 01, 2014 7:45 pm
by prosthotoothist
Thanks for all of your information and suggestions. I have placed two photos in photobucket to see if they will show what I am concerned about as far as lack of sharpness and detail in my test renderings. By the way, this project at this stage is very much a work in progress as you can easily tell, so please don't be too critical of my amateurish work! Here is the photobucket link: http://s1273.photobucket.com/user/prost ... t/library/ The photo on the left is a 300% enlargement to better show the "jaggies" along the edges of the sculpture material. The photos show the results of rendering at 1366 X 768 for 8 hours and 40 SL. Hopefully, this information will help provide an improvement in my renders.

Thanks,

Tom

Re: Another question regarding quality of render

Posted: Tue Dec 02, 2014 1:26 am
by itsallgoode9
Looking at your image I don't think anything looks like anything is being rendered incorrectly.
at a resolution of 1366, those tiny hard diagonal edges are literally being defined by a width of 1 or 2 pixels, which as you can image, won't produce a smooth edge. Along with that, the "artifacts" are showing up where there is a high contrast, which is expected.

Here's that section of your image in photoshop. I drew two extra lines that are similar to the jagged edges you're seeing in your image. Both are drawn with a 1 pixel line tool in photoshop. The smoother one has anti aliasing on and the rougher one has anti aliasing turned off. You can see that the 1px anti aliased line looks almost exactly like your edge

Image

If you look closely at that tooth image that Tom posted, all of his edges are slightly blurry, if you zoom in, which is why you see no aliasing artifacts. This works in his image because he is working with a solid image and not just a single pixel line.

You might be able to selectively blur those areas of aliasing artifacts to help smooth it out. On another hand, the projector you're image is going to be shown on most definitly won't be sharp enough to ever notice these issues.

Re: Another question regarding quality of render

Posted: Tue Dec 02, 2014 1:33 am
by Mihai
Well, SL 40 :) Please have a read in the docs about SL, you really don't need to go that high. Stop the render when it's clean enough for you and if there is a tiny bit of noise it's not usually a problem a little bit of denoising in PS can't solve. If the render stops and there is still noise, you can always resume the render at any time.

http://support.nextlimit.com/display/mx ... in+Maxwell

And as for jaggies, if you zoom in 300% of course you will see "jaggies" but it's because those pixels are simply magnified. Do you see any jaggies at 100%? It's also a high contrast area where you will see some kind of jaggies also in real photos. Here is an example and it's not that high contrast but you can see some jaggies if you look very closely on the legs of the chairs in the sand:

Image

Don't worry about this, especially if you're going to use a projector that isn't even HD. Everything will get pretty blurred compared to what you see on your computer screen anyway.

Re: Another question regarding quality of render

Posted: Wed Dec 03, 2014 12:32 am
by prosthotoothist
itsallgoode9 and Mihai,

Thank you both for your very detailed explanations regarding my concern about rendering "jaggies". I guess that I have a problem in my mind about extremely sharp details since most of my experience, over an almost 35 career in dental education, was with the use of photographic slides of dental objects. Since dental structures are relatively small, we always tried to achieve the sharpest images possible. These images were projected using a non-digital projector, so there was no pixel-related resolution issue. If we achieved a sharp image, that is what we saw on the screen. So, I guess I am making a problem for myself that really shouldn't exist if I realize that the projector to be used can do no better than 1366 X 768 resolution images on the screen.

Again, thank you both so much for "clarifying" the issue for me. I certainly won't be doing any more 40SL and 8 hour renders!

Regards,

Tom

Re: Another question regarding quality of render

Posted: Thu Dec 04, 2014 2:29 pm
by feynman
For projectors used in academic institutions (and we have many different ones), I always render at 2 x the resolution of the projector. Never had any complaints with quality. Always looks fantastic.