[Radiance-general] Raw images from radiance package?

[Ji Zhang]

Dear Greg,

Just want to confirm with you that the ambient parameters of rtrace, such
as  -ab, -ad, -ar, -lw, etc, may also affect the RGB radiance values that
will be output to the text file in this case, is it?

To Vera, you can use the -f* option of vwray to specify its output format,
and you can also use the -f** option of rtrace to specify its input and
output format (see the menu for both programs).

For example, the following batch script gives you the position of the point
where each ray (shooting from the viewpoint towards one of the pixels in
the image) intersects with a given scene surface and also the normal of the
ray at that point. The output format for vwray is "float", and the input
and output format for rtrace is "float" and "ascii", respectively.

##############################
vwrays -ff -x 600 -y 600 -vf view.vf \
| rtrace @./image.opt -opd -ffa -n 2 \
`vwrays -d -x 600 -y 600 -vf view.vf` \
.scene.oct > ./rtrace_output_-opd.txt
##############################

Ji


On Fri, Mar 21, 2014 at 6:01 AM, Greg Ward <gregoryjward at gmail.com> wrote:

> Matlab does have a module for reading HDR images.  See:
>
>
> http://www.mathworks.com/help/images/working-with-high-dynamic-range-images.html
>
> You can also convert to other formats as I said using pvalue, or go
> directly to floats using rtrace.  For example:
>
> vwrays -vf myview.vf -x 100 -y 100 | rtrace -h scene.oct > myresults.txt
>
> would create an ASCII list of RGB values, one per pixel for the given view.
>
> Best,
> -Greg
>
> *From: *Vera Liu <lizzielyh at gmail.com>
>
> *Subject: *Re: [Radiance-general] Raw images from radiance package?
>
> *Date: *March 20, 2014 12:11:00 PM PDT
>
>
>  Hi Greg,
> Thank you so much for the prompt reply! I want to generate some simulation
> images for my project, but Matlab can't read in the .oct file or .pic file
> generated by oconv and rpict. So I was wondering what I should use to
> output raw images with linear light coordinates and then extract the pixel
> values. As you mentioned  the gile generated by using rpict should be the
> raw format? Or I could use rtrace option to get the pixel values?
>
> Best,
> Vera
>
>
> On Thu, Mar 20, 2014 at 10:40 AM, Greg Ward <gregoryjward at gmail.com>wrote:
>
>> Of course.  Radiance pictures as output from rpict, etc. are linear
>> floating-point in RGBE format.  You can change these to ASCII or binary
>> floats using the pvalue program.  If you don't like the 1% precision this
>> gives you, there is the option of outputting to 4-byte IEEE float or ASCII
>> from rtrace.  You can couple this with vwrays if you want to generate
>> specific views.
>>
>> What is your purpose?
>>
>> -Greg
>>
>> *From: *Vera Liu <lizzielyh at gmail.com>
>>
>> *Subject: *[Radiance-general] Raw images from radiance package?
>>
>> *Date: *March 19, 2014 10:45:42 PM PDT
>>
>>
>>  Hi,
>> I know there are functions like ra_bmp to transfer radiance files to bmp
>> files or other formats. I'm wondering if there's a way to generate raw
>> images from the .rad files so that the output is in linear light
>> coordinates?
>> Best,
>> Vera
>>
>>
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>>
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