View Full Version : need help with lightprobe

08-07-2003, 11:22 PM
Please will someone tell me what's going on here?
Loading a lightprobe image created in LW with Skytracer 2 baker, I get the following (crazy sky distortion coming to a point) when I rotate the heading in image world (pic#1). I was rotating it to try to get the same sky image to appear in the background as in pic #2. Do Lightprobes not work as background also?

How can I use the lightprobe AND get the sky background it was created from -- and the sky in the same position relative to the model in the scene, so the light will be from the correct angle, and agree with the background??

please help,

08-09-2003, 08:04 AM
Very interesting question, Indeed.

I was thinking about it, and well I am some what of a newbie, I would like to know what the LightProbe is ?

And What your using the light probe for ?

I wish I could answer the question.... :confused:

08-10-2003, 12:35 AM

08-10-2003, 03:08 AM
How did you go about making a light probe? The way a globe is flattened will determine what method it needs to be mapped in LW - ImageWorld is for probes. I don't think skybaker makes a probe-type image, try textured environment / spherical or cylindrical mapping.

zapper - these are light probes:

08-10-2003, 02:47 PM
Thanks for that link, it looks very useful for the general subject if not for this particular problem.

Skybaker does make lightprobes, there is a choice for it in the skybaker dialog in 7.5. Here's what it looks like loaded into the image editor. It's an .hdr, so i can't load it into other software to get a bigger pic, but you can see it looks similar to other such images.

There's nothing in the manual that helps me with this problem, i spent quite a long time looking. If someone knows anything about this, please help, cause I've also searched the archives here for a long time and did not come up with any answers.


08-10-2003, 03:04 PM
I looked but didn't see it the first time - that's very cool

08-10-2003, 03:39 PM
Ok I checked out that website (very nice pdf article, worth printing), and pulled one of the lightprobes from the site into lW and also got the same effect when rotating it's heading in Image World.

So, I'm wondering, is there
a) something wrong
b) its supoosed to look like that in viper, and you're supposed to composite another background image for the background

if b, then, how do you get the right positioning for the light probe, and does that wierd coming-to-a-point effect affect the lighting...?

here are the pics of both the lightprobe hdr image (from image editor)

08-10-2003, 03:39 PM
....and the wierd effect of rotating the heading in image world (from Viper)


08-10-2003, 03:44 PM
Does it render the same when you F9? I've seen several cases where Viper was very different -

08-10-2003, 04:00 PM
well...this isn't from the render, which looks ok with the image probe in the default position (except for the ugly background, in any position), it's the info from image world via viper.

But the option is there to rotate the lightprobe image, and when you do, you get this in viper. Problem is, I will need to rotate the light probe image to get the correct lighting, and there is no way I know to tell what's happening when I do rotate it, if this is the feedback LW provides!
It would take a heck of a lot of radiosity renders to test the lighting this way...!


08-10-2003, 04:28 PM
well I get the same pinching no matter what Lightprobe image I use, even Debevecs'. (Viper looks the same as the render) I guess that part is supposed to stay behind the camera :D

08-10-2003, 06:14 PM
here's what happens when the pinched part is behind the camera...these two test views were done with the lightprobe heading rotated as follows:
1) 298 deg (convergence in view)
2) 118 deg (convergence behind camera)

as you can see, these rotations are 180 deg apart. The convergence is obviously reflected on the surface of the sphere on the far right (which has a 10% reflectivity), coming from behind the camera, so it DOES AFFECT the image. Not good.

Something is definitely amiss...


08-10-2003, 08:02 PM
yea, no 3D programs are perfect, maybe that's the best you can do with lightprobes -
I suggest that it's work-around time, use a spherical map for reflections, use LightGen to make lights out of an HDR image, something like that

08-12-2003, 07:52 AM
after reading the links to the url's giving I under stand a liitle more

thanks again