Getting black image from 'direct sun only' on DDS

I am following Sarith tutorial on matrix-based methods, and trying to get images from ‘direct sun only’ by using
part of the scripts on 5PM. But not sure why the images come all black(the model is a room with a south facing window and the rendered images through 2PM does show the sun patches in the room)

(OS is Windows)

The rendered image by rvu shows that the oct file I guess has correct geometry of the model and the suns.

cnt 145 | rcalc -e MF:1 -f -e Rbin=recno -o solar.txt > suns.rad

oconv room.rad suns.rad > roomSuns.oct

rcontrib -w- -ab 1 -ad 256 -lw 1.0e-3 -dc 1 -dt 0 -dj 0 -ffc -n 8 -x 600 -y 600 -ld- -o “\Matrices\d\hdr\img%03d.hdr” -e MF:1 -f -b rbin -bn Nrbins -m solar roomSuns.oct < “view.rays”

gendaymtx -d -m 1 “USA_NY_New.York-Central.Park.725033_TMY3m-0.wea” > “USA_NY_New.York-Central.Park.725033_TMY3m-d.smx”

dctimestep -o “Images\d\hdr\img%04d.hdr” “\Matrices\d\hdr\img%03d.hdr” “USA_NY_New.York-Central.Park.725033_TMY3m-d.smx”

suns.rad content is like this:

void light solar 0 0 3 1e6 1e6 1e6
solar source sun 0 0 4 0 0.994522 0.104528 0.533
solar source sun 0 0 4 0.206773 0.972789 0.104528 0.533

solar source sun 0 0 4 -0 -1.60812e-16 1 0.533

Hi Ali,

I wonder if this has something to do with the missing Five-Phase flag (-5 0.533) in your gendaymtx:

I tried recreating the issue with the exercise files and did not get black images. Here is what I did:

The results from that simulation are below:

I am not sure how precise this result would be as there are only 145 suns being considered (as pointed out in Fig 17 of the tutorial). If you absolutely have to use Windows, you could still do a higher order MF simulation by using rcontrib with the -M option, splitting the modifier file into multiple chunks, and then running several consecutive instances of rcontrib. I haven’t tried it but I believe this will work. It will require some custom scripting and might take a really long time to finish.

Finally, although I called it DDS in the tutorial, that 2-Phase method is not exactly following the DDS approach as there are no additional calculations being performed to interpolate sun positions.


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Yes Sarith, the missing (-5 0.533) flag was the issue. Thanks.