Image-Based Lighting in Lightwave and Radiance
Eliza Ra

Lightwave 6
Image-based lighting can easily be done using either Lightwave 6 or Radiance.  In Lightwave 6, you will need the Lightwave 6.0b patch, the ImageWorld plug-in, and any light probe image.

NOTE: To import image probes properly into Lightwave they must have the .pic extension. If you grabbed a sample from Paul Debevec's site and it has an .hdr extension, simply rename it to .pic
Turn Radiosity on. Either after or before you setup your scene, you may select 'Backdrop' in the 'Settings' menu and click on 'Add Environment' to add LW_ImageWorld.  You may then adjust settings for your environment, which requires no geometry.

In Radiance, you must insert an environment geometry.  You will need to map your light probe image onto our environment geometry.  The following code illuminates our scene based on the lighting information contained in the light probe image.

. . .
# This uses angmap to wrap itself around an object
void colorpict env
7 red green blue env.pic sb_u sb_v

# This creates a 'glow' material with the 'env' modifier called 'env_glow'
env glow env_glow
4 1 1 1 0

# This is the box environment object with 'env_glow' applied to it
!genbox env_glow boxenv 500 500 500 -i | xform -t -250 -18 -250
. . .

As an example, now we'll map a high-dynamic range image to the environment, figure out the camera angle, and finally output a picture.


void colorpict uff
9 red green blue sb_u sb_v -rx 90

uff glow uff_glow
4    .5    .5    .5    0

!genbox uff_glow boxenv 10 10 10 -i | xform -t -5 -5 -5

% oconv uff.rad > uff.oct
% rview -av 2 2 2 uff.oct &

This will show you an image of your scene at the default view (notice that there are no light sources in this scene).  -av specifies the amount of light globally present in the scene.  For more parameters go to the Radiance website. In rview, you can rotate your camera using r x (where x is an angle in degrees). For examples, if you type r 90, you'll rotate 90 degrees clockwise.  For more commands to manipulate your scene in rview click here.

Once you have your camera angle, you can type 'view [viewfile]' to save the view in 'viewfile'.  Now you can view your scene with the specified view by just typing 'rview -vf [viewfile] -av 2 2 2 [file.oct]'

To make it crispy clean, you will need to tweak with various image settings described here.  To make a picture, try this:

% rpict -av 2 -aa .15 -ps 8 -ar 80 -aw 40 -ad 800 -as 200 -av 2 2 2 -vf [viewfile] file.oct > file.pic

Here, rpict produces a high-dynamic range image using 2 ambient bounces, which should be the minimum for any scene using image-based lighting.  Now view the .pic file by typing 'ximage file.pic'.

You should consult the Radiance website for more detailed information.