Could RTRACE produce two outputs (picture and values)?

Hi Mirjam,

pixel values in a hdr file are nothing but binary-coded triplets of irradiance data in three channels (RGB) if you render your irradiance hdr image. If you have an image file containing these illuminance values, you can extract the data to e.g. ASCII columns using pvalue -o Outcome.hdr. pvalue does not interpret the data and thus does not care about it being irradiance or radiance, it just converts between codings. The -o makes sure to use the original pixel values in case any exposure correction had been appiled (uncommon with irradiance maps).

The advantage in using a sensor grid, not an image, to calculate illuminance is that you would typically use a rather coarse grid, with less sensor locations to be calculated. This saves time per sensor, allowing higher accuracy at each location. So you may prefer very high ambient settings for a 10 x 10 sensor grid over a 1024x1024 pixel image, which may force you to reduce the accuracy. This assumes that you do not loose relevant information from the reduced resolution (e.g. a sensor may happen to be shadowed by a thin frame, which would lead to underestimates if interpolation between sensor values is applied).

You can also use pvalue -r to create a hdr image from your ASCII columns of irradiance / radiance values. In that case, some information on the x/y dimensions must be given.

Of course, recoding pixel values does not allow you to translate irradiance into radiance or vice versa...

Cheers, Lars.


Dear all,

Just a short question, unfortunately I wasn't able to find the answer on the Radiance-community:

*Is it possible to create two outputs using RTRACE: *

-a .hdr picture and

-a text file containing illuminance values.

In case of a virtual plane, rtrace has to be used instead of rpict (as explained in the Radiance Tutorial). Now, I'm doing the same simulation twice in order to get 2 outputs which takes a lot of time. Isn't it possible to create 2 outputs through only 1 simulation?

If not, could pvalue help me on this one? And if yes, how? Or would pvalue only would give me luminance values?

First simulation:

echo " Rtrace illuminance "

vwrays -x $Dims -y $Dims -vf viewfile.vf \

> rcalc -e '$1=$1; $2=$2; $3=0.75; $4=$4; $5=$5; $6=1' \

> rtrace -w -ab 3 -fac -I -ov `vwrays -d -vf viewfile.vf -x $Dims -y $Dims` scene.oct > Outcome.hdr

Second simulation:

echo " Rtrace illuminance values "

vwrays -x $Dimstable -y $Dimstable -vf viewfile.vf \

> rcalc -e '$1=$1; $2=$2; $3=$3; $4=$4; $5=$5; $6=1' \

> rtrace -w -I -h -ov -ab 2 `vwrays -d -vf viewfile.vf -x $Dims -y $Dims` scene.oct | rcalc -e '$1=$1*179' > Outcome.txt

Thanks in advance for your help!

Best regards,