rvu image resolution question

[Christopher Jones]

Hello SPOT Users,

I am wondering if it is possible to change the rvu resolution. Currently, rvu is using 512 sampling. I am getting a somewhat grainy picture with some strange blotch effects. See the attached screen capture.

Thanks for your assistance!

[Zack Rogers]

Hi Chris,

The rvu program is really meant to be an interactive Radiance viewer and typically not used for final high resolution and high quality images.  Although, in my experience it is still quite useful for generating smaller images for comparison and analysis during the design process.  I then go to higher quality renderings as I am fine tuning final design options.

Anyways, it is easy to generate high quality renderings from your SPOT models.  One method is as follows:

1)  Find the "rview_day.bat", or "rview_geom.bat" file in your SPOT project directory and open in a text editor.  The "..day" and "...geom" terms relate to whether you generated the interactive rendering from the geometry or daylighting results page.  The "..day" file may be better to use if it exists because it will utilize all the ambient data already generated by SPOT.

2) The file will look something like:

cd /D C:\Users\Zack\Dropbox\SPOT\SPOT_v5.02 & prompt SPOT: & Title SPOT Calculations & cls

set PATH=.;C:\SPOT\bin

set RAYPATH=.;.\luminaire;C:\SPOT\lib

Title SPOT Daylight Rendering & cls

rvu -vf views\sw.vf @calc.opt -ab 2 -af ambfiles\spot\12_21_12.00_1_Z1.amb octrees\spot\12_21_12.00_1_Z1.oct || pause

change the final line to an rpict call (instead of rvu) like so:

rpict -vf views\sw.vf @calc.opt -ab 2 -t 60 -x 1024 -y 1024 -af ambfiles\spot\12_21_12.00_1_Z1.amb octrees\spot\12_21_12.00_1_Z1.oct > images\e12pm_sw.hdr || pause

The changes are highlighted.  The -t 60 command will make it report the % progress every 60s on the command line.  The -x 1024 -y 1024 set the desired resolution.  These are maximum values as the image proportions are kept (ie a typical wide rendering will be set by the -x resolution).  The > images.... command directs the final hdr image to the images directory.  You can name this whatever you want and can open these HDR files using the "C:\SPOT\bin\wxfalsecolor.exe" program that comes with SPOT.

3) The quality of the rendering is determined by the Radiance parameters you are using in your SPOT project.  On Advanced Options, if you set the variability to H and quality to H the simulations will take a bit longer but you will get much nicer renderings in SPOT.  You can also just raise the Radiance parameters for a final image but you have to remove the reference to the ambient file, otherwise it will just use lower quality ambient data.  In this case, your final line might look like:

rpict -vf views\sw.vf @calc.opt -ab 3 -aa .1 -ar 100 -ad 2048 -t 60 -x 1024 -y 1024 octrees\spot\12_21_12.00_1_Z1.oct > images\e12pm_sw.hdr || pause

Here I raised some parameters (ambient bounce to 3, ambient accuracy to .1 etc.) and then removed the reference to the .amb file.  This rendering will take a bit longer as it won't be benefiting from existing ambient data, but with the raised Radiance parameters will be much higher quality.

To further improve the rendering you could add these lines to pre-generate higher quality ambient data and then generate a larger resolution rendering that gets filtered down to a better quality lower resolution.  This is how the radiance "rad" command would work.

rpict -vf views\sw.vf @calc.opt -ab 3 -aa .1 -ar 100 -ad 2048 -t 60 -x 64 -y 64 octrees\spot\12_21_12.00_1_Z1.oct > NUL

rpict -vf views\sw.vf @calc.opt -ab 3 -aa .1 -ar 100 -ad 2048 -t 60 -x 4096 -y 4096 octrees\spot\12_21_12.00_1_Z1.oct > images\e12pm_sw.unf || pause

pfilt -m .25 -x /4 -y /4 images\e12pm_sw.unf > images\e12pm_sw.hdr

del images\e12pm_sw.unf

4) Save your .bat file as a different name, perhaps "rpict_day.bat".  Execute by double-clicking the batch file.

SPOT uses a full Radiance engine and so you will be amazed at how nice you can get these renderings.  Hope this helps.

Happy Rendering!

Zack

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Zack Rogers, P.E., LEED AP BD+C    

Daylighting Innovations, LLC

808 S. Public Road, Suite 200

Lafayette, CO 80026
(303)946-2310

www.daylightinginnovations.com

[Christopher Jones]

[Christopher Jones]

Zack,

Very cool. Thanks for those useful pointers.