Global illumination with Ogre: Reflective Shadow Maps

[andrew85]

This is a simple implementation of the paper: Reflective Shadow Maps by Carsten Dachsbacher and Marc Stamminger (University of Erlangen-Nuremberg). Despite this particular techinque is quite old, many other subsequent papers are based on this idea. I used Ogre and his deferred shader framework to build this app. By computing the indirect illumination with a low resolution image, the frame rate reaches 20 fps @ 1920x1080 (on a Radeon HD 5800).
If someone is interested, I can provide the source code on my blog http://3dgraphicsprogramming.blogspot.com/

Please find the source code and the precompiled binary at http://db.tt/pX6fpSwu

[lordsme]

Very interesting!!

[hedphelym]

Very good work! I really enjoy your blog.
It would be nice with source code, or a sample application that we can run.

I'm very interested to see how this would work on our highpoly scenes.

[andrew85]

I hope to release a sample application in a couple of weeks. Thanks for the feedback!

[mkultra333]

That sounds very interesting. I have VSM spotlights, deferred point lights, and a background ambient light with SSAO, but some reflective light would be excellent. What's the rendering cost like?

[andrew85]

It totally depends on the number of VPLs and the resolution of indirect light buffer, as this technique is fill-rate limited. With 256 VPLs, 512x512 indirect buffer and 512x512 RSM, the cost is 17ms, but you have to tolerate some amount of "blur" across discontinuities. I have no time to provide a complete chart for the cost, but you will be able to play around with the app very soon (sorry but I'm busy with my master thesis ).
Actually I'm planning to improve this demo with a multi-resolution approach that would be far better both in quality and performance (see, for example, Greg Nichols and Chris Wyman. "Multiresolution Splatting for Indirect Illumination." ACM Symposium on Interactive 3D Graphics and Games).

[jonim8or]

Its a very interesting technique. One question, though. In the paper I see the color of the lit walls reflected on the statue, but due to the positioning of the statue in the screenshot I can't see it there.
Can you post another screenshot that shows in which aspect this lighting technique is very good?

And how does this integrate with the Deferred Shading? is it an addition, or a replacement of the shadows/lighting functionality that is there already?

[Sgw32]

I'm interested in using your system. Can it work on Ogre 1.6.4, not the latest release?

[andrew85]

You mean color bleeding, here it is a screenshot. You can see reddish reflections on the statue and on the other wall. Shame on me for the shadow... it is not antialiased . The technique plugs and plays with deferred shading. You have deferred direct lighting/shadows and the indirect illumination added optionally. As you can see in the screenshot there's a turn on/of button. If I turn off, I'm just using the ogre deferred shading framework provided with the SDK.
@Sgw32: I'm using Ogre 1.7.1, but I did not try with older versions

[andrew85]

I released the code of this demo http://db.tt/pX6fpSwu. Check out my blog http://3dgraphicsprogramming.blogspot.it/.

This demo relies on Ogre 1.7.1 and its deffered shading system. As I stated in the previous posts, it is a very basic technique ( Based on "Reflective Shadow Maps" by Carsten Dachsbacher and Marc Stamminger ) for a faster and more advanced implementation ( or to adapt it to your needs ) you can contact me ( baldacci85'at'hotmail'dot'it).

[Xavyiy]

Thanks for the release Andrew!

I'll definitely play with that in a future.

Any chance of a precompiled demo?

Xavier

[andrew85]

Glad of your interest. Yep, I'll publish a binary demo as soon as possible.

[drwbns]

I built from source and the demo is really really dark in DirectX and OpenGL. All resources loaded correctly but are there some missing resources? Same result with Ogre 1.8 latest and 1.9 latest. I notice you said you're using 1.7. Is deferred shading different in latest versions? Also, I don't have the overlay options you have in your screen shot, maybe a different build you have?

[andrew85]

Sorry a paramater was wrongly set. Dowload again from this link http://db.tt/pX6fpSwu and let me know. (I cant check myself right now). (Please note that, for now, the binary is compiled in debug mode, and that in the demo are included and activated a motion blur and dof effect )

The overlay pannel was included in a previous version, maybe I can include it again. In the provided demo, there is a single spot light and 256 virtual points lights that simulates the indirect illumination.

[drwbns]

I got the same result, just really dark, no lights. No errors in the Ogre.log.

screenshot07212013_051834887.jpg

Strangely lit corner outside -

screenshot07212013_052136467.jpg

[andrew85]

It seems there is a problem with ssao. I disabled it. However consider also that there is only a light source. Try to move it to see different result ( either from the source code or moving the mouse while pressing the right button) .

Here it is a couple of screenshot I get on my laptop:

rsm1.jpg

rsm2.jpg

I am going to upload the new version.

About the light outside, consider that this method do not account for indirect light occlusion, thus there may be some light bleeding outside.

However this method could be further improved to account for this fact (for example with:"Imperfect shadow maps").

[andrew85]

Ok. I disabled all other effects except global illumination. Download again from http://db.tt/pX6fpSwu. Give it a try and let me know.

Here it is another screenshot:

screenshot07212013_194521364.jpg

[andrew85]

Another sample scene:

133217_178558178830612_8054888_o.jpg

[nickG]

why so long?
3 years..

[nickG]

reupload please