[Radiance-general] Calculating pixel value at a specific location in an image

[Chris Humann]

My apologies for not being more specific when posting earlier.   I  
also just realized that I missed a similar post in the archives from  
May 2008.  However, the latter posts don't quite answer the question  
at hand.

I have a series of images produced from a script in which the previous  
image octree is over written prior to the proceeding rpict call.   
Given the latter condition, I don't think  vwrays connected to rtrace  
will work as I don't have the corresponding 'octree' file.
I suppose I could write a Python Script to parse the pixel location  
and its associated value, but that seems a bit over kill for what  
seems should be a straight forward, one line task.


> I'm trying to use 'pvalue' to calculate a pixel value at a specific  
> x,y location in an image by piping  'pvalue' through 'rcalc',  and  
> am stuck on the correct syntax to use for the expression, '-e', in  
> 'rcalc':
>
> pvalue -o -h  -H  rendered_image.hdr | rcalc -e  
> '(x_location,y_location

Thanks again.
Chris


On Apr 5, 2010, at 2:53 PM, Chris Humann wrote:

> Greetings all,
>
> I'm trying to use 'pvalue' to calculate a pixel value at a specific  
> x,y location in an image by piping  'pvalue' through 'rcalc',  and  
> am stuck on the correct syntax to use for the expression, '-e', in  
> 'rcalc':
>
> pvalue -o -h  -H  rendered_image.hdr | rcalc -e  
> '(x_location,y_location)'
>
> Has anyone tackled this in the past?
>
> As always, thanks!
>
> Chris
>
> Christian Humann ~ Associate
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>
> On Mar 30, 2010, at 8:31 AM, Jack de Valpine wrote:
>
>> Hi All,
>>
>> I have compiled the latest Radiance release (4.0) on Ubuntu 9.10.  
>> For those who are interested, I have placed a tarball on our ftp  
>> site which can be downloaded as follows:
>> go to: ftp.visarc.com
>> user: u36117396-rad
>> passwd: rad-r40
>> get: rad4R0-linux-ubuntu.tgz
>> This is a temporary location for the short term. I will check in  
>> with Greg about making this available through www.radiance- 
>> online.org.
>>
>> Please see the README for some basic notes on installation. Note  
>> that I have also included the documentation directory.
>>
>> Please let me know if there are any questions and I will answer  
>> them as I am able.
>>
>> Regards,
>>
>> -Jack de Valpine
>> -- 
>> # Jack de Valpine
>> # president
>> #
>> # visarc incorporated
>> # http://www.visarc.com
>> #
>> # channeling technology for superior design and construction
>>
>>
>> Jack de Valpine wrote:
>>>
>>> Hi All,
>>>
>>> I just wanted to report that Radiance 4.0 compiled with no  
>>> problems on the following Linux variants:
>>> Fedora Core 5 - yes an old file server but still running strong
>>> Ubuntu 9.10 - the only thing that I had to do was install the  
>>> following packages to get the compile to work smoothly:
>>> csh
>>> libx11-dev
>>> -Jack
>>> -- 
>>> # Jack de Valpine
>>> # president
>>> #
>>> # visarc incorporated
>>> # http://www.visarc.com
>>> #
>>> # channeling technology for superior design and construction
>>>
>>>
>>>
>>> Thomas Bleicher wrote:
>>>>
>>>> On Thu, Mar 18, 2010 at 10:19 PM, Fitzsimmons, Rob
>>>> <Rob.Fitzsimmons at fiserv.com> wrote:
>>>>
>>>>> Yes, I usually launch X11.app
>>>>>
>>>>> Is there any harm in having all other binaries as 4.0, but  
>>>>> keeping the rvu
>>>>> 3.9 version?
>>>>>
>>>>
>>>> There should not be a big problem. But you will not be able to  
>>>> use the
>>>> new fancy multi-process option. I don't know if rad can pass that  
>>>> on
>>>> to a rvu but if it would try at some point you will get an error.
>>>>
>>>>
>>>>> That’s working for me now. Correct me if I’m wrong but rvu is  
>>>>> only used to
>>>>> display in X11 is not used in producing an hdr image.
>>>>>
>>>>
>>>> No. rvu is interactively producing the image. To display an image  
>>>> you
>>>> would use ximage. Have you tested that yet? Or glrad? I think those
>>>> are the only apps that need xlib.
>>>>
>>>> Regards,
>>>> Thomas
>>>>
>>>> _______________________________________________
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>>>>
>>>
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