Dear Radiance users,
I would like to generate a shadow range image to show the shadow movement
in a period of time.
I searched some reference and some of them indicate "pcomb" is able to
combine a bunch of pictures into one hdr image.
So I tried to use pcomb script to combine the hourly daylight images I have
generated, but the overlaid part completely become dark color.
I am not sure is this the correct method to do shadow range because I am
not familiar with this script.
I am wondering if you have any tips or examples can actually generate
shadow range image?
Cheers,
···
--
Wen-Hsin Chang
Hi Wen-Hsin,
What is a "shadow range image?" Can you send a URL with some examples? As near as I can tell from a Google search, it is just an average image, which is similar to the sum of images you would get from pcomb with multiple HDR inputs and no special arguments. You could also generate an image of minimum values, where anyplace a shadow fell at any time would appear dark.
The pcomb tool can combine HDR images in many different ways. You have not shown how you are currently using this tool (the exact command) or what output you are expecting versus what you are getting. This is essential information for anyone to help you with your problem.
Best,
-Greg
···
From: Wen-hsin Chang <[email protected]>
Date: September 29, 2016 5:09:46 PM PDT
Dear Radiance users,
I would like to generate a shadow range image to show the shadow movement in a period of time.
I searched some reference and some of them indicate "pcomb" is able to combine a bunch of pictures into one hdr image.
So I tried to use pcomb script to combine the hourly daylight images I have generated, but the overlaid part completely become dark color.
I am not sure is this the correct method to do shadow range because I am not familiar with this script.
I am wondering if you have any tips or examples can actually generate shadow range image?
Cheers,
--
Wen-Hsin Chang
Wen-Hsin
If you have created the individual pictures as regular high quality rpict
renderings then the cumulative effect of multiple shadow against sunlit
surfaces can result in very dark core areas for the shadow. You can try
pcond with a linear response function (pcond -l input.hdr > output.hdr) to
bring the bright values back into a range where you can identify details in
the shadow.
A more advanced setup for this type of image is to create images with hard
shadows (low -ab values and -av of 0 0 0). You can extract the shadow
portion of these images as a difference to a base image. Then you add up
all the shadow-only images and overlay that as a last step over a rendering
with soft shadows to show the geometry. In this last step you can also
apply a color tint to the shadow image to make it stand out against the
background.
I don't know if there is a ready-to-use script out there to do all of these
steps. I expect it will take a bit of tinkering to find the right
combination of commands and command line arguments for your purpose.
Hth,
Thomas
···
On Thu, Sep 29, 2016 at 7:09 PM, Wen-hsin Chang <[email protected]> wrote:
Dear Radiance users,
I would like to generate a shadow range image to show the shadow movement
in a period of time.
I searched some reference and some of them indicate "pcomb" is able to
combine a bunch of pictures into one hdr image.
So I tried to use pcomb script to combine the hourly daylight images I
have generated, but the overlaid part completely become dark color.
I am not sure is this the correct method to do shadow range because I am
not familiar with this script.
I am wondering if you have any tips or examples can actually generate
shadow range image?
Cheers,
--
Wen-Hsin Chang
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