Autodesk LIGHTSCAPE, Manual

Page: 223 / 362

Creating Images
215
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2. To enter a path and filename, do one of the fol-
lowing:
•
Enter a path and filename for the rendered image in
the Output File Name box
• Click Browse and navigate to the location in the
Open dialog, enter a filename, and click Open.
•
Select the output format and pixel depth required.
3.
Select an image resolution from the Resolution
list.
4. To define a custom resolution, select User De-
fined from the Resolution list and enter the dimen-
sions for the image in the Width and Height boxes.
5.
To increase the number of antialiasing samples,
select the appropriate level from the Antialiasing
Samples list.
Note: Increasing the antialiasing level will increase
your rendering time.
6.
Click OK.
Rendering with Ray Tracing
With Lightscape, you can create high-quality ray
traced images that render effects such as specular
reflections and refraction through transparent
materials.
In addition to the Image Resolution and Antialiasing
options described in “Rendering with OpenGL” on
page 214, the following options are available when
you use ray tracing.
Ray Trace Direct Illumination
This option ray traces direct light contributions
from lighting sources (the sun and luminaires
marked for ray tracing). Use this option to correct
shadow aliasing problems and provide additional
enhanced lighting effects, such as highlights on
nondiffuse surfaces. For more information, see
Chapter 11, “Radiosity Processing,” and Appendix
D, “Reflection Models.”
Remember that the time required to generate images
can increase significantly with the number of light
sources that are ray traced.
Lightscape uses different antialiasing algorithms depending on whether or not ray tracing is used. If
ray tracing is not used, OpenGL image generation uses either a software or (if available) a hardware
accumulation buffer. It jitters the original images a number of times by a slight subpixel amount and
then averages these images to produce a single high-quality image.
This process requires the image to be displayed n times, where n is the square of the antialiasing level
selected. For example, an antialiasing level of 2 displays the image four times to create the final image.
A level of 10 displays the image 100 times (taking 100 times longer to create than the non-antialiased
image).The ray tracer uses a different adaptive scheme that is more efficient for this process. So, with
the ray tracer there is no direct correlation (as with the OpenGL method) between the antialiasing level
and the time required.
Antialiasing Algorithms in Lightscape
Antialiasing Samples list