help with HDRI lighting

(stephen2002) #1

I get the concepts behind the technique and have been playing around with it recently. I can’t seem to figure out if there is an option to convert the 6-image lightprobe from terragen into the MHDR file. When I use the option in the program that eeshlo made to convert to MHDR, the “Save MHDR” stays greyed out even after I have loaded a light probe.

edit— I just figured out that it must be downsampled first.—edit

I would also like to convert the probe into an environment map that I can load into Blender for reflections. I don’t want to use the probe as the environment itself though, so the box around the enviornment thing dosn’t help.

Anybody have any ideas?

<font size=-1>[ This Message was edited by: stephen2002 on 2002-03-16 10:56 ]</font>

(theeth) #2

you can convert 6 hdr to a 360 degree probe with the third tab “Cube to Probe” in his program. Just make sure all the 6 .hdr are in the same folder.
Then, you can convert the probe to ENVmap with the 4th tab “make diffuse envmap”.


(eeshlo) #3

I guess I will add a direct cube-to-envmap conversion routine, the cube-to-probe-to-envmap method will add some distortion.
You only need to click “make Envmap” after converting the cube to a lightprobe image, nothing else, this will directly convert the probe to a Blender environment map, don’t forget to set an appropriate size before you click it. Also play around with the gamma and exposure sliders to get a good contrast and brightness. The resulting envmap is to be used on an object with an empty which has been ‘rotation cleared’ (alt-r)

(stephen2002) #4

Also, I was just experimenting with your script with a desert environment that I am working on. It has a crisp blue sky with a bright sun. It is fairly flat, because it is a desert. There are some dunes in the distance. When I run the lightprobe through the script, all of the lights generated are, well, blue! The colored lights turn white objects blue (and distorts the colors of the rest), and then it dosn’t look right. Aside from the coloration, the lighting looks really nice with the shadows in the right spot.

Any ideas?

(eeshlo) #5

This has more to do with the terragen plugin or terragen itself. Ideally the exposure settings in Terragen should not have an effect on the resulting HDR, but seemingly this can’t be bypassed by the plugin. In the documentation I mention that things like ‘SIMPLE HAZE’, ‘ATMOSPHERIC BLUE’ often need to be reduced, and ‘LIGHT DECAY/RED’ could maybe be increased, it probably is also better to alter the sun glow power/amount. The effect you get is the cause of the sky itself acting too much as a lightsource.
Although the conversion method will also add its part, the information in the HDR is of course very much reduced in the downsampled MHDR, the Mitchell filter is probably best for this.
The HDRshop lightgen plugin method will probably produce a better result, but I did not release that yet, I was waiting for the new python API…

(Switchblade) #6

This sounds interesting- can I get a web address for this?

Kib_Tph (webmaster dude), how about some sort of plugin directory/downloads center so that we can all access the various plugins that everyone talks about? Would that be too much of a strain on the server?


(theeth) #7

A page with links to all the scripts and plugins repository would be nice indeed.