View Full Version : Optimal Solution for Photorealism


EnginArslan
10 October 2008, 02:18 AM
First of all, hello to everyone; its my first post on cgtalk :)

I wanted to ask a question about rendering. I have a school project, which is preparing an ad for a cellphone. I want to model my cellphone and and light & render it to get photorealistic results. My shot will primarily be focused on the cellphone itself, no enviroment interaction or anything just; a shot of a cellphone animated in front of a dark background.

I will be using 3ds max. I was wondering if it is possible to get convincing (photorealistc) results by only using Raytracing + IBL (and maybe final gathering) and some spotlights(or area?), or is it necessary for me to go for GI for photorealism? I am trying to go for an optimal solution; realistic results without too much of a render time.

What would your recommendations be?

Thanks!

mister3d
10 October 2008, 11:31 AM
You can turn off Gi completely for it as your cellphone reflects mainly but if you have too dark shadow simply add a light to make it brighter. I've seen many people doing studio lighting with IBL, but I think it's wrong: in studio they use softboxes mainly, not a forest for a reflective environment. Study how to light reflective objects in a studio. What you need is just area lights (maybe just one, or two).
For photorealism try this: bevel all the corners to catch specular highlights; nothing is perfect, even a new cellphone; try model as accurate as you can; unwrap every element and provide color, specular and bump minimum for every surface; some imperfection in texture is a plus; provide depth if field as it would happen in real cameras.

EnginArslan
10 October 2008, 06:46 AM
thank you for your tips, as you have suggested I am focusing more on enhancing my geometry, adding chamfers to the edges where necessarry. I will also try to create as accurate maps as possible. As for IBL; a studio hdri to enhance the reflections, or clouds to dramatize the effect in reflections maybe? I will try and see. thanks

eldonaldo
10 October 2008, 08:30 AM
i'd suggest some kickass modelling and shading in the first place.

eldonaldo
10 October 2008, 10:42 AM
well.. why don't you just show us something. I think its easier to give you some advice if we can refer to your work.

israelyang
10 October 2008, 08:31 PM
I don't see the point in using a 'studio HDRI' (if by this you mean an HDRI consisting of a studio lighting setup).
You can recreate it by simply setting up some area lights, this way you can adjust the size and intensity of them directly in your 3d software and not having had to go back to adjust your HDRI for changes.
http://www.neilblevins.com/cg_education/overbright_card/overbright_card.htm

good luck

mister3d
10 October 2008, 09:38 PM
I don't see the point in using a 'studio HDRI' (if by this you mean an HDRI consisting of a studio lighting setup).
You can recreate it by simply setting up some area lights, this way you can adjust the size and intensity of them directly in your 3d software and not having had to go back to adjust your HDRI for changes.
http://www.neilblevins.com/cg_education/overbright_card/overbright_card.htm

good luck

I agree...and you usually want to keep studio lighting simple. The reason for this is that your major subject is not lighting but the object itself. That's why they shoot big reflecting objects like cars in days with clear sky not to break the form. If you make the sky reflecting in the cellphone, I would make it rather neutral as it will attract too much attention imho.
Still, I would suggest you lighting the planes.

http://img373.imageshack.us/img373/6006/cellscopysz7.jpg (http://imageshack.us)
http://img373.imageshack.us/img373/cellscopysz7.jpg/1/w700.png (http://g.imageshack.us/img373/cellscopysz7.jpg/1/)

EnginArslan
10 October 2008, 05:31 AM
mister3d, eldonaldo, israelyang;

The project that I am working on is actually for a motion graphic class(so no obligation for 3d there). But the reason I am going for max & mental ray usage is to be able to enhance my knowledge on cg lighting. Because of that desire of knowledge, I guess I tend to overcomplicate things. I think I need to analyse product shots more throughly before going for any setup. And for the area lights thing, you are obviously right. I suppose to be able to change the size and the shape of your area lights is a huge advantage, nothing to be dismissed. This project of mine will consist of not just the cellphone, but musical instruments such as piano, trumpet and guitar doing basic motion. I will post some wip if you would like to, as I progress. As much as I like to achieve a aesthetic (not cheessy at least) solution, I also want to become more acquainted with the usage of mental ray. Maybe shading part would prove to be chalenging for me (I suppose especially for the trumpet).

so no HDRI for me then :)

maxwill1977
10 October 2008, 11:09 PM
Hi there,

Id stick with the studio hdri setupís, that with a skylight and FG set-up correctly can give stunning results in no time at all. The maps as you know contain actual studio light set-ups shot with a rather swanky Spheron VR camera. They contain all the subtle soft box and light details.

http://www.hdri-studio.com/ (http://www.hdri-studio.com/)

Make sure you set-up the map correctly in the bitmap parameters (spherical mapping) and also configure the range in the Linear white point output box. Also make sure this figure is the number used in the RGB level on the bitmap output parameters.

Also make sure the res of that environment lighting map is low res. You could try the SIBL approach. This software is great at outputting all the source you need even if you donít use it fully. Fantastic tools. This is a wicked resource:

http://www.hdrlabs.com/sibl/ (http://www.hdrlabs.com/sibl/)


Try adding a little camera effects too like glare, good resource is here:

http://masteringmentalray.surpass.nl/content/view/36/10/ (http://masteringmentalray.surpass.nl/content/view/36/10/)

Oh, and that books pretty darn good to if you using MR (Iím assuming you are?)

If things are looking a little hot, try using the MR photographic exposure control in the effects panel. It great at controlling light distributing and light burn.
Cheers,

Will.

mister3d
10 October 2008, 02:38 AM
Maxwill1977б, could you please explain what those HDRI provide you can't do with simple area lights? I can't see any reason to use them. And yet the lights are fixed in them. Is there an HDRI that suits any product shot needs? I doubt that. All you have to do is hoping that one of those HDRI will magically fit.
The studio lighting is a subject that must be studied with corresponding books and strictly relates to 4 main types of materials, such as transparent, mirror-like materials, translucent and diffuse. All those need different approaches in lighting. The simpliest is a diffuse type as light diffuses uniformly around the surface and usually doesn't create much problems, but if you light a mirror-like metal it won't work. You must know exactly what you are doing - how the form is revealed through a reflection. There is almost no guesswork here imho.
Ok, here is an example of watches test lighting I did. It's rather rough but shows the concept imho: the form is revealed, not broken, and you can tell it's a mirror-like metal. Though if you have critics I am pleased to hear them of course.
http://img124.imageshack.us/img124/3474/watchesub5.jpg (http://imageshack.us)
http://img124.imageshack.us/img124/watchesub5.jpg/1/w268.png (http://g.imageshack.us/img124/watchesub5.jpg/1/)

maxwill1977
10 October 2008, 12:05 PM
Thats a good question, i guess the truth is its all down to the way you work and what creatively works. Remember you can combine IBL with other lighting. I like the ibl approach. Using these light ibl sets simply offers a range of pre set studio environments that typically work for all manner of 'product shots' they are very quick to change too. I'm not a photographer but i know there are some rule of thumb techniques for studio lighting. I guess these sets adhere to them.




I work with this approach as well as area lighting, sky etc etc. they all serve different purposes dependent on the creative requirements. Sometimes in production you need a quick fix solution that produces believable results.




I know you can do this with area light, adding maps to control colouration etc etc, you can obviously do this too with the new MR light surface and FG, the options are endless. I've even made ibl sets with light surfaces with the wrap around lens shader, that works too. (dont forget to change framebuffer to 32bitdepth to save out full luminance range)




what do you think of the Studio HDRI sets? Have you looked at the samples?




Try everything!




W.

israelyang
10 October 2008, 04:07 PM
Hi Will and OP
if you go here http://www.hdri-studio.com/neutral.html
and click on the blue text links (for Neutral and Gels), you can see how the HDRIs look like.
You can recreate that in your program by creating basic geo planes (2 to 3 of them in this case) and give them an incedescent/ambient color value of higher than 1, with any colours you want, and render with final gather. By giving the planes a color value of higher than 1 you are getting the same effect as a high dynamic range image.
You can in fact model any shapes to use as your light source. Personally I think this approach is much more flexible, and you can always reuse your own set up.

mister3d
10 October 2008, 04:47 PM
Maxwill1977, I have looked at the samples. Maybe it's a good starting point using those HDRi. I like you can see reflections of real softboxes. Having them is definitely beneficial, but from my limited experience using ibl, even created by yourself is a bit cumbersome as you have to paint those effects in, you can't easily evaluate the family of angles, and in general you move away from a realistic lighting to painting. But it's my own opinion and if you get good results with these HDRI, why not?
Israelyang, I agree it's a good idea to create your virtual studio and reuse light rigs and other stuff if you work with studio lighting often.

maxwill1977
10 October 2008, 10:09 AM
Yeah id agree with that for sure. Above all it always good to remember all these systems have their places in CG. All of which are highly regarded and established within different production environments.




Id recommend reading up on all the methods at your disposal for a good all round knowledge. That way you can progressively refine your techniques dependent on the task at hand.




There's limited recourse for mental ray. If you want books go for the 'Rendering with Mental Ray and 3ds Max' (Joep van der Steen) for ibl, ive found 'The HDRI Handbook' (Christian Bloch) also very useful for background and techniques. Both these books give good technical details for the various tools available. Also print out those PDF's that come with 3ds max for mental ray. Not the easiest to follow at times but good for detail and great bedtime reading!




W

sundialsvc4
10 October 2008, 02:30 PM
One tip that might really help you along is... model for your presentation and your medium.

Nothing more. Nothing less.

If you are doing "a motion graphic," then the characterisics of that presentation are going to define the limits of what is worth-doing and what is extraneous.

Since your final medium is "a video screen," it's also valid to point out that "your final deliverable is going to be a 2D arrangement of colored pixels on a screen." Any way that you can get there is equally "good."

When you create an image, critique it against reference photos. (Be sure to compare it to (digital...) photos, which are flat, not the actual object in your hand.) Look at the light. When you "see" that "something's not right," try to put your finger on it... give it a name. (Read Ansel Adams' definitive books on "The Zone System...")

Once you have identified a particular characteristic that is "wrong," think about what might be the easiest way to change those pixels.

You're not here to "model reality," except as a possibly-useful exercise. There are many ways to get those pixels to look differently. Some of the "at first blush" ideas might be computationally-horrific. But maybe there's a way to "cheat..." ("Cheating" Is Good.)

They say that the two best tools in a CG professional's tool-chest are Time and Budget.

EnginArslan
10 October 2008, 05:52 PM
mister3d, eldonaldo, israelyang, maxwill1977,

thank you all for your advices, In the end I have chosen to use a simple plane and an area lights for my project; it still requires some adjustments but I am glad to say that I am quite pleased with the results. The plane I have used for illumination is an arch and desgin material (3ds max) with a glow shader added to its self illunimation slot. The phone in the end is actually pretty much 2d so lighting doesnt work as good as I would like it to work there, but for now I am calling it quits. Sorry for not being able to reply before, it had been a really busy week with lots of assignments. Here is the result:

http://www.youtube.com/watch?v=7ATz4Fk2jUc

sundialsvc4;

these are really some good advices for a budding vfx artist like me. I totally agree on your viewpoint. as they always say: "if it looks right it is right". It seems that our library has some Ansel Adams books, I will definetly check them out.

Thank You very much.

mister3d
10 October 2008, 01:26 AM
For me, the mobile phone part looks the best. :D You could make it lighter in general though.
The piano part would benefit from DOF in the beginning, and the camera could be a bit smoother.
You see, your horn dissapears because it lacks something to reflect. By placing several reflectors around you would make it shine more. The same about the guitar - the dark part dissapears.
But not bad for a start.

EnginArslan
10 October 2008, 03:43 AM
Yes, I suck at animation :) horn dissaperance was intentional, I applied a fog using the z depth information, maybe I would remove it. The guitar definetly needs some backlight. Thenk you for your feedback.

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