Realistic Light and Shadows Using Vizard and 3DS Max

[jde]

Hi Folks,

General question:

What techniques do you generally use to create realistic lighting and shadows in environments when using Vizard in conjunction with other modeling programs like 3DS Max? How would you go about creating light and shadows in a modeling program and matching that lighting as closely as possible in Vizard?

More specific question:

For my purposes, I need to simulate the effect of a sun casting shadows on a virtual hedge maze environment and ensure that the lighting in both Vizard and 3DS Max match as closely as possible. I created a kind of secret garden maze in 3DS and used only an "IES Sun" set to cast shadows together with some radiosity. This gave me some nice directional shadows coming from a single light source.

When I import the maze into Vizard, some lighting needs to be provided using Vizard's lighting options; however, I'm using the environment for experimental purposes so I need the lighting in Vizard to either (a) match the lighting I created in 3DS as closely as possible, or (b) simply turn up the brightness of my model in Vizard rather than specifying light sources per se.

Basically, I want to simulate the effect of a single light source (the sun) casting shadows, without introducing other light sources that would cast incompatible shadows (if Vizard actually supported shadows) -- our participants might pick up on the weird incompatibility and not behave as they would in an environment with appropriate lighting and shadows.

Does anyone know any of the details of the default lighting in Vizard (i.e. if you don't create any lights, what kind of lighting is used by default and where are the lights located in the environment? does the default lighting just crank up the brightness on all objects uniformly, or does it simulate a light source that would illuminate a surface differently depending on the angle of incidence?)

Could I match the lighting in 3DS and Vizard by changing the intensity of appropriately located directional lights?

Does anyone have any general suggestions regarding how to match lighting in 3DS and Vizard?

NOTE: I'm aware of the shadow casting module that is available but it's not powerful enough to have all of the objects in the maze cast shadows on other objects, and on themselves.

I hope this post is useful to people working with lighting...

Thanks,
Jon

[hengshan.li]

Hi jde,

I meet the same problem that we have to make a photoreal model for experiment. However, when I convert the 3d model from 3D max into IVE, the texture disappeared. Could you give me some advice about how you resolve the problem please? Thank you very much!

[jde]

i've spent about 6 months trying to get support from Autodesk on this issue and they've decided to put the issue on their product development schedule because they can't find a solution. they've also stopped responding to my emails entirely despite the fact that we've purchased a service contract. i'll be sure to post a solution on this site if they ever provide me with one. in the meantime, i'm thinking about purchasing the finalrender plugin for 3ds to see if that rendering engine solves the problem.

[turgutm]

No responce?

[saajaja]

You have to fake everything in virtual reality. Turning the lights up is done separately from casting shadows.

There isn't much perceptual benefit of having over-the-top realistic lighting. The Shadow.py module that WorldViz has works on dynamically changing objects, but it isn't very realistic. If you're working with static objects, or ones that don't completely change form, you can use images as shadows.

For two methods of doing this, if you're running Vizard 4 (3 might have it), press Shift-Ctrl-O and open gallery.py and tutorial_shadows.py.

gallery.py demonstrates a simpler method, but it only works if the object is casting the shadow on a uniform plane, like a human casting a shadow on the floor. The shadow helps the viewer understand where the human is in relation to the floor.

tutorial_shadows.py is more flexible, but it is limited by hardware constraints. Some graphics cards can support eight projectors (shadows) at once; mine supports three. It can cast shadows on nonuniform objects and account for their curvature.

Getting objects to cast shadows on themselves in realtime is just not something I've heard of anyone out there doing. The rendering just doesn't happen quickly enough to happen in realtime. Until hardware improves dramatically, we'll have to keep hacking.