Frequently Asked Questions


Recent FAQs



I'm using Blender 2.36 under windows and b/rad is not working: what should I do?

Make sure that you have installed Python 2.3 (Blender 2.36 is not compatible with Python 2.4).

After that, go to My Computer/Control Panel/System/Advanced, and
click on the "Environment Variables ..." button.
click for image

After that, add the new two environment variables PYTHONHOME and PYTHONPATH, pointing them to the Python folder (default C:\PYTHON23)
click for image
and update the PATH environment variable.
click for image
Then, install the pywin32 package, put the content of the brad archive in .blender/scripts, open Blender, open a scripts window, Update menus and launch b/rad. Don't forget to update the program preferences and to create the export folder (default C:\BRAD).
Click here to see a picture of my desktop running brad and the Desktop Radiance version of rview.

I've installed the radiance macos x binaries (running macos 10.3.7 and python 2.3). blender 2.36, xfree86, and imagemagick via fink. radiance is working. blender is working. ((-:
BUT if i try the "sky preview" i get "ximage: /Applications/Blender/ cannot open display" in the console window.
is it possible to make x11-applications able to open the x-display via blender/python o­n macos x?

Reply from Giulio (GRAZIE!!!): -1- make sure that ximage works at all on your system (just a silly check, but you never know) -2- if ximage works, the solution is then to start blender from the terminal. to do that you need to go into: in fact is a folder folder as all macosx applications (to browse it you need to ctlr+click on it and ask for 'show contents' in the contextual menu) when you are into just type: ./blender the GUI starts and everything works. plus you are able to see error messages in the terminal window (good if you need to fix a problem) only small problem is that the window is larger than the screen, but you can adjust the menu position by dragging them.

Hi, Francesco.
At first, I'd like to thank you for BRAD! It is a very nice software, exactly what I was looking for.
I'd like to know how to include a localization at SIMULATION menu. I 'm living in Brasilia/Brasil and there is no South America city. Could you help me?
Thanks in advance
Evangelos Christakos

Hi Evangelos!
There is no interface at the moment to add locations, but you can easily add a new site by editing the locations.dat file inside .blender/scripts/brad/radiance/loc.
You will need to enter the location name, latitude (positive for North of equator), longitude (positive for West of Greenwich meridian) and time zone (number of hours, again positive for West of Greenwich meridian).
The next time you will start blender and b/rad, you'll find your newly added location in the list.

Hi, I live in Brasilia-Brasil, so I want to setup simulations to my city. As I didnt find this city in menu, I edited locations.dat and added Brasilia data (l=-16 (south) 47 (west) and 45 , is it right?
Congratulations for BRAD it is a wonderful ideia!
Thanks a lot

Hi Vangelis, Yes, what you did is right. I'm happy you found brad useful for you and more happy that you figured out by yourself how to add new locations to the simple database. Have fun!, Francesco

How does gensky work internally?

Here is a description of the gensky behaviour and of the formulas that it uses (as far as I can understand from the gensky.c code). gensky at the moment behaves this way (I hope not to make any error ...): 1. it can model uniform skies 2. it can model CIE standard clear skies (as described in CIE 110-1994) 3. it can model CIE standard overcast skies (as described in CIE 110-1994 and previous standards) 4. it can model non standard intermediate skies, whose definition is contained inside src/gen/gensky.c and /src/gen/ (I don't have a reference about where the intermediate sky definition was taken from) If it is given zenith radiance (-b) and solar radiance (-r), gensky uses directly the CIE formulas or the intermediate sky formula, since all the sky distribution parameters are already defined, but it is not very usual to have measured sequences of such weather data. DIRECT CONTRIBUTION from the sun If we provide gensky with horizontal direct irradiance (ees), solar radiance (solarbr) is computed with the following formula: solarbr = ees/(6e-5*sin(sunaltitude)) If we only specify location and time, gensky uses the following formula: solarbr = 1.5e9/SUNEFFICACY*sin(sunaltitude) if (1.147 - .147/sin(sunaltitude) > .16), otherwise 1.5e9/SUNEFFICACY*.16 where SUNEFFICACY = 208 /* illuminant B (solar dir.) */ Additionally, if the sky is intermediate, the previous value is multiplied by 0.15 (i.e the so called /* fudge factor! */) DIFFUSE CONTRIBUTION from the sky If neither zenith radiance (zenithbr) nor horizontal diffuse irradiance (eed) are given, the Krochmann equation is used for the CIE OVERCAST SKY: zenithbr = 8.6*sin(sunaltitude) + .123 [kcd/m^2] (Krochmann) CIE 110-1994 also reports equations by Kittler and Nakamura, Oki et al. for this purpose. For the CIE CLEAR SKY the LBL equation (Karayel, Navvab, Ne'eman, Selkowitz) is used (here the Linke Turbidity appears for the first time): zenithbr = (1.376*turbidity-1.81)*tan(sunaltitude)+0.38 [kcd/m^2] (Karayel, Navvab, Ne'eman, Selkowitz) CIE 110-1994 also reports a lot of equations that should be chosen according to the climate condition in the location of interest (Kittler, Dogniaux, Krochmann, Liebelt, Gusev, Nagata, Nakamura Oki et al.), but gensky only uses the LBL one. For the INTERMEDIATE SKY, gensky computes the average of the overcast and CIE clear zenith radiances. At the end, the computed resulting value is divided by SKYEFFICACY D65EFFICACY = 203 /* standard illuminant D65 */ SKYEFFICACY = D65EFFICACY /* skylight */ If the horizontal diffuse irradiance (eed) is provided, then gensky computes the zenith radiance by using the following formula: zenithbr = eed/(normfactor*PI) normfactor = 7/9 for CIE OVERCAST SKY while for CIE CLEAR SKY and the INTERMEDIATE SKY, normfactor is computed by using two different polynomial approximations. For the CIE CLEAR SKY, CIE 110-1994 suggests two different polynomial approximations by Kittler (as said, "for practical purposes") and by Gusev (for polluted atmosphere): both of them are not used by gensky.

Hi, I would like to work with Evalglare (which can be found here: under Cygwin.I’ve compiled Evalglare, but I have some problems while using it.I’m a beginner with Cygwin, so I’m not sure that I’ve compiled Evalglare correctly. Did someone already compiled Evalglare for Cygwin? Thanks in advance, François Cantin

I haven't compiled it for cygwin yet, but it is certainly doable. I will add it to my TODO list and will get back to you as soon as I will do it.

I've installed the radiance 3.8 on macos x 10.4.10 with blender 2.45 and python 2.5.1. Radiance and blender are working just fine. However, when i tried to use b/rad after follow instruction of b/rad, when reached "Misc/Blended RADiance" there is a error saying that "Python script error : check console". Regarding to previous posts, with blender 2.36 , there is a need to use python 2.3. However, I have no idea whether that should apply for mac osx as well. It would be very kind of you if you can kindly give me some advice on this.

Hi, sorry for the problem :-) Unfortunately I don't have a macos x box, so I am unsure about the solution but I'll try. Could you try saving the "brad" folder to a location outside the .scripts folder, then save the "" script inside the .script folder and edit it so that the brad_path variable points to the folder containing the "brad" folder? Please let me know how it goes. Regards, Francesco

its a really good work to join Blender with Radiance.
I've tried to work with BRAD, but I've an error (blender console):

Compiled with Python version 2.5.
Checking for installed Python... got it!
<string>:112: SyntaxWarning: name 'config_path' is assigned to before global dec
<string>:112: SyntaxWarning: name 'brad_path' is assigned to before global decla
<string>:112: SyntaxWarning: name 'configparserok' is assigned to before global
<string>:143: SyntaxWarning: name 'lang' is assigned to before global declaratio
<string>:143: SyntaxWarning: name 'editor_path' is assigned to before global dec
<string>:143: SyntaxWarning: name 'config_path' is assigned to before global dec
<string>:143: SyntaxWarning: name 'export_path' is assigned to before global dec
<string>:143: SyntaxWarning: name 'debug' is assigned to before global declarati
<string>:143: SyntaxWarning: name 'brad_path' is assigned to before global decla
<string>:143: SyntaxWarning: name 'radiance_binaries_path' is assigned to before
 global declaration
<string>:143: SyntaxWarning: name 'radiance_library_path' is assigned to before
global declaration
<string>:143: SyntaxWarning: name 'configparserok' is assigned to before global
<string>:704: SyntaxWarning: name 'X' is used prior to global declaration
<string>:709: SyntaxWarning: name 'Y' is used prior to global declaration
No existing configuration file: using default configuration.
Traceback (most recent call last):
  File "<string>", line 208, in <module>
  File "C:\Brad\brad\brad\", line 428
SyntaxError: Non-ASCII character '\xe8' in file C:\Brad\brad\brad\ o
n line 428, but no encoding declared; see
ml for details

Where is the problem -Anyone can help me?
I have Win XP, Blender 2.44 (2.49) and Python 2.52 (I've tried version 2.62)...



Hi Rafal, please try erasing any accented character inside the file and see if this solves your problem. Best, Francesco