- Radiosity Calculation
- After all the surfaces are oriented
in the right direction, the materials are assigned and the
luminaires are defined, the scene is finally ready for radiosity
- But dont jump out of your
seat just yet. You still have to set a few parameters before
Light* can calculate the solution. Luckily, Light* comes with
a Process Parameters Wizard to aid you. This is recommended
for initial testing of a scene. When doing a final render,
it is recommended that you manually set the various parameters
to fine tune the solution.
- When youre ready, go to
Process ® Parameters
, here youll
see this dialog:
- Click on the Wizard button
to let Light* take you through a series of parameters. Just
follow the on-screen instructions, its pretty self-explanatory.
- After clicking Finish, go
to Process ® Initiate or click on:
- At this point, Light* will prompt
you if you want to save the current .LP (preparation)
file. Choose yes and let Light* initialize your scene. After
initialization is finished, youll notice your most of
the surfaces are now sub-divided. Go to File ® Save
again. This time Light* will prompt you for another file name.
Notice the extension at the bottom of the dialog. It is now
.LS (solution file). Save it again with the same file
- Click on the shaded mode button
to view your model in shaded view:
- Now go to Process ® Go
to began calculation. Light* will start to calculate the light
distribution of each luminaire and the light reflection of
all the surfaces. If youre fairly new to Light*, it
is very neat to watch this process. It looks like each luminaire
is being turned on, one at a time.
- Notice the status line at the
bottom of the screen. This tells you how many percent of light
has been distributed. Allow Light* to continue its calculation
until 85% of the lights are distributed. It is not necessary
to go all the way to 100%. 85% will give you a fairly accurate
representation of the final scene.
- If at any time during the calculation
youre not happy with the lighting in the scene, go to
Process ® Stop to interrupt the process. Next,
you can double-click on whatever luminaire that needs changing
and adjust its photometric setting.
- At this time you can also change
the materials of the surfaces if necessary. But it is advisable
to reset & re-process (Go) the solution if youre
changing the materials because the reflected color of the
new material wont be updated at this point.
Note: When in
the Solution stage, you can no longer move any objects in
the scene because the meshing has already been processed.
If you decide to move anything, you have to go back to the
.LP file and move them there and re-initialize the solution.
- When youre done making
the changes, click on Go button again to continue the calculation:
- Here is an example of what my
scene looks like at 54% completion:
- At 83% completion this is how
I am satisfied with the solution
at this point.
- If you like at this point, you
can orbit / zoom around your model to check your model without
having Light* recalculating everything. This is truly the
beauty of radiosity processing. Since the light data is stored
in the meshes themselves, you are free to move about the scene
without having to re-render the scene.
- You can also click on the Ambient
button to turn on the rest of the ambient lighting in the
- Also, click on the Textures
button to see how the textures look in your processed scene
- When youre satisfied,
youre are ready to raytrace the scene. Go to File
- Here, youre presented
with a rendering dialog. I usually set my Antialiasing
Samples to 5. Set the desired output resolution and name your
image. Be sure you check the Ray Tracing option. Leave
the default Ray Bounces value at 10. When youre
ready, click on Ok. Depending on what Antialiasing
value youve set, the time it takes Light* to render
each image will vary.
- Although this is an easy way
to raytrace an image, it is also very slow, because the image
is being displayed on the screen as its being raytraced.
The faster and more efficient way to do this is through the
command line with LSRAY.EXE. This is the raytracing executable
of Light* that comes with the program. This is only recommended
for those who are familiar with command line driven operations.