[Radiance-general] How to generate the image of shadow range?

[Thomas Bleicher]

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 <x.wenhsin at gmail.com> 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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>
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