[Radiance-general] rpict image rendering problem

[Ji Zhang]

Dear Radiance experts,

I'm testing rendering radiance scene using rpict with Radiance 4.0 in Mac OS
10.6.7

Problem A:
I'm using the following rpict command:
rpict  -vf /test/view.vf -w  -aa 0.2 -ab 3 -ad 2048 -ar 128 -as 512 -x 500
-y 500 /test/scene.oct > /Users/oat/Desktop/image.jpg

However, I have the following problem with the png file generated:
1. the surfaces not facing the sun directly looks like being burnt
2. there're a lot of black splotches along the edges and corners of the wall
3. the image has a lot of jagged edges
4. it cannot be open in photoshop but it can be previewed in Mac OS

the preview of this png file as screen-captured is like:
https://2omvuw.bay.livefilestore.com/y1p8T69Ib9EOtRETgqUwtZrJ_hfoKx1uDj4hkHKIFICcIAZ17CFilr8bRaY0n6zURTGQpmdYWRALT2rnvmiz3cUmUDR8IG_-xBd/Mac%20OS%20png.png?psid=1


Problem B:
If I render the image as .hdr file it still have the same problem 1 to 3 as
mentioned above when I preview it in Mac OS. But the hdr image can be open
in Photoshop and appears quite right with less severe splotch problem.

The rpict command:
rpict  -vf /test/view.vf -w  -aa 0.2 -ab 3 -ad 2048 -ar 128 -as 512 -x 500
-y 500 /test/scene.oct > /Users/oat/Desktop/image.hdr

The hdr image as opened in Photoshop is:
https://2omvuw.bay.livefilestore.com/y1p5J22wHNNnuKciUzj5slOchjNGAKcZ7NclFvCojDvwVmrgoglis8BQt4RB9BTaPLpbk3_3sjaJ11-TSpsM6ndEVuA5FKwZp3Y/Mac%20OS%20hdr.png?psid=1



Problem C:
if I add a ground surface into the scene, the hdr image as rendered will
have a lot of bright splotches along the bottom of the wall surfaces (the
ground surface is positioned 0.3m lower than the floor surface of the room):
https://2omvuw.bay.livefilestore.com/y1perNd2uKYSrsH2hXoIZqyVynQkw1Eid2ULgDb-gY3VJ-Cb9ANIhZ1ZucPz7rZQynAypp_Fjskp1gN9pbgNneAp7A7Hbxzwa0B/Mac%20Os%20hdr%20_with_ground.png?psid=1

The maximum dimension of the scene is around 100m after adding the ground
surface.


I'd like to ask:
1. why the png or jpg file generated using rpict in Mac OS can be previewed
but cannot be open in Photoshop?
2. why the png, jpg or hdr image generated using rpict in Mac OS looks
"burnt out" when previewed?
3. why only the hdr image file can be opened in Photoshop and appears
normal?
4. why does the additional ground surface cause the splotches? and how to
correct it?
5. how to get a clean hdr image with smooth surfaces that have no splotches
and jagged edges?
6. What are the key rpict parameters to control the image quality?


Can you kindly help to take a look and advise me the source of problem and
the solutions?

Thank you!

Ji
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://www.radiance-online.org/pipermail/radiance-general/attachments/20110426/3d056202/attachment.html>