can the sun material identifier "solar" be specified in rcontrib?

Hi Ji,

If you keep working through Axel's tutorial, you will see that the distribution for a given sky condition is applied as a separate step using output from gensky or gendaylit piped into genskyvec. Rtcontrib is being used to calculate the skypatches for a unit/uniform distribution. These unit results are then multiplied by the output from the genskyvec command. So the actual output/distribution for a given sun/sky is not part of the rtcontrib calculation.

Hope this helps,

-Jack

···

--
Jack de Valpine
President

Visarc Incorporated
www.visarc.com

channeling technology for superior design and construction

On 12/30/2013 7:50 AM, Ji Zhang wrote:

Dear list,

Following Axel Jacobs' Rtcontrib tutorial (up to pp.19 so far), I used a sky created by gendaylit rather than an overcast/uniform sky used in the tutorial.

The hdr image i got by combining the 145 sky patch hdr images shows a dark spot around the sun position. I assume this might be because only the "-m sky_glow" argument is specified in rcontrib, thus the image generated doesn't include the contribution from the sun spot.

However, when I include an additional "-m solar" argument (the material identifier for the sun geometry) to the rcontrib command I only got strange sky patch images.

May I ask why this approach is not correct? and how to visualize the contribution from the sun spot?

Thanks!
Ji

The shell script (without sun material identifier):
##############################
# create a sky description using gendaylit

gendaylit 1 1 9 -a 1.37 -o -103.98 -m -120 -W 70.0 130.0 -O 1 > ./skies/sky_gendaylit.rad

# copy all lines in the original sky.rad and past in the newly generated sky_gendaylit.rad above

oconv ./materials/testroom.mat ./objects/testroom.rad ./skies/sky_gendaylit.rad > testroom_gendaylit.oct

# viz the contribution from each of the 145 patches in the gendaylit sky from the fisheye viewpoint

DIMS=600

vw="-x $DIMS -y $DIMS -vf ./views/sky.vf"

vwrays -ff $vw | rcontrib -bn 146 @./rtc.opt -ffc \
`vwrays -d $vw` -V+ -f tregenza.cal -b tbin \
-o ./images/patches_gendaylit_skyview/p%03d.hdr \
-m sky_glow ./testroom_gendaylit.oct

# use Andy McNeil's approach to merge the 145 hdr images

pcomb $(for i in {001..145}; do \
echo "./images/patches_gendaylit_skyview/p$(printf "%03d" $i).hdr"; done) \
> ./images/sky_pcomb_gendaylit_skyview.hdr

falsecolor -ip ./images/sky_pcomb_gendaylit_skyview.hdr -s 10000 -l cd/m2 -n 10 \
> ./images/sky_pcomb_gendaylit_skyview_fc.hdr
##############################

The shell script of rcontrib with the sun material identifier included:
##############################
vwrays -ff $vw | rcontrib -bn 146 @./rtc.opt -ffc \
`vwrays -d $vw` -V+ -f tregenza.cal -b tbin \
-o ./images/patches_gendaylit_backview_withSun/p%03d.hdr \
-m sky_glow -m solar ./testroom_gendaylit.oct
##############################

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Thanks, Jack! seems I need to working on the tutorial a bit more before I
raise the question ...

···

On Mon, Dec 30, 2013 at 10:20 PM, Jack de Valpine <[email protected]> wrote:

Hi Ji,

If you keep working through Axel's tutorial, you will see that the
distribution for a given sky condition is applied as a separate step using
output from gensky or gendaylit piped into genskyvec. Rtcontrib is being
used to calculate the skypatches for a unit/uniform distribution. These
unit results are then multiplied by the output from the genskyvec command.
So the actual output/distribution for a given sun/sky is not part of the
rtcontrib calculation.

Hope this helps,

-Jack

--
Jack de Valpine
President

Visarc Incorporatedwww.visarc.com

channeling technology for superior design and construction

On 12/30/2013 7:50 AM, Ji Zhang wrote:

Dear list,

Following Axel Jacobs' Rtcontrib tutorial (up to pp.19 so far), I used a
sky created by gendaylit rather than an overcast/uniform sky used in the
tutorial.

The hdr image i got by combining the 145 sky patch hdr images shows a
dark spot around the sun position. I assume this might be because only the
"-m sky_glow" argument is specified in rcontrib, thus the image generated
doesn't include the contribution from the sun spot.

However, when I include an additional "-m solar" argument (the material
identifier for the sun geometry) to the rcontrib command I only got strange
sky patch images.

May I ask why this approach is not correct? and how to visualize the
contribution from the sun spot?

Thanks!
Ji

The shell script (without sun material identifier):
##############################
# create a sky description using gendaylit

gendaylit 1 1 9 -a 1.37 -o -103.98 -m -120 -W 70.0 130.0 -O 1 >
./skies/sky_gendaylit.rad

# copy all lines in the original sky.rad and past in the newly generated
sky_gendaylit.rad above

oconv ./materials/testroom.mat ./objects/testroom.rad
./skies/sky_gendaylit.rad > testroom_gendaylit.oct

# viz the contribution from each of the 145 patches in the gendaylit sky
from the fisheye viewpoint

DIMS=600

vw="-x $DIMS -y $DIMS -vf ./views/sky.vf"

vwrays -ff $vw | rcontrib -bn 146 @./rtc.opt -ffc \
`vwrays -d $vw` -V+ -f tregenza.cal -b tbin \
-o ./images/patches_gendaylit_skyview/p%03d.hdr \
-m sky_glow ./testroom_gendaylit.oct

# use Andy McNeil's approach to merge the 145 hdr images

pcomb $(for i in {001..145}; do \
echo "./images/patches_gendaylit_skyview/p$(printf "%03d" $i).hdr"; done) \
> ./images/sky_pcomb_gendaylit_skyview.hdr

falsecolor -ip ./images/sky_pcomb_gendaylit_skyview.hdr -s 10000 -l cd/m2
-n 10 \
> ./images/sky_pcomb_gendaylit_skyview_fc.hdr
##############################

The shell script of rcontrib with the sun material identifier included:
##############################
vwrays -ff $vw | rcontrib -bn 146 @./rtc.opt -ffc \
`vwrays -d $vw` -V+ -f tregenza.cal -b tbin \
-o ./images/patches_gendaylit_backview_withSun/p%03d.hdr \
-m sky_glow -m solar ./testroom_gendaylit.oct
##############################

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_______________________________________________
Radiance-general mailing list
[email protected]
http://www.radiance-online.org/mailman/listinfo/radiance-general