[vtkusers] Re: displaying a 3-channel dataset as an image

[Goodwin Lawlor]

Hi Gala,

I'm not sure exactly what you're trying to do but you can calibrate your 
image using the methods SetOrigin and SetSpacing.

SetOrigin sets the lower left position of your image:
image->SetOrigin(long,lat,0);

SetSpacing sets the size of your pixels:
image->SetSpacing(d_long, d_lat, 0);

hth

Goodwin


wind wrote:
> Okay, that makes sense. Now I need to give each point of that image a 
> latitude / longitude coordinate.... Is there a way to specify point 
> coordinates for an image? I can do it with a dataset that has only one 
> component and display it with a lookup table, no problem. But now I need 
> to set an RGB color for each of those points to see the image. 
> 
> The reason I need to do this is that I'm mapping aircraft flight tracks 
> onto satellite imagery. I want the satellite image to appear on the XY 
> plane. That satellite image has to be in the coordinate system of the 
> flight track : latitude / longitude. Is there a way to do that or no? In 
> the worst case scenario, I guess I could go with a grayscale image, but 
> I really would like a color one. 
> 
> Here's the image read in after I converted the data into a TIFF image, 
> but it doesn't scale properly, because it has to be scaled using lat/lon 
> grid that comes with the data. The grid is already defined for every 
> point on the image. You can see what I'm trying to do. The colored line 
> is the flight track itself, the white line is the ground track and now I 
> want that satellite image underneath it. 
> 
> Thanks, 
> 
> -- Gala 
> 
> 
> On Feb 28, 2007, at 11:38 AM, Goodwin Lawlor wrote:
> 
>> wind wrote:
>>> Hello, I have a file that has three sets of scalars in it that I 
>>> would like to display as an image with each set mapped to red, green 
>>> and blue color respectively. The data file contains different 
>>> channels from a satellite. I've read the data into memory and now 
>>> have three arrays of 8-bit numbers. I can combine the data into a 
>>> single array if I have to. Is there a way to tell VTK to display that 
>>> array as an RGB image?
>>> Thanks, -- Gala
>>
>> Hi Gala,
>>
>> You can use vtkImageAppendComponents. See how it's used here:
>>
>> http://www.bioengineering-research.com/vtk/VHPREADER.TCL
>>
>> to read planar rgb images from the Visible Human Project.
>>
>> Note you have to add the blue channel first, then green, the red.
>>
>>
>> hth
>>
>> Goodwin
>>
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> 
> Gala Wind
> 
> (301) 614-6221
> 
> wind at climate.gsfc.nasa.gov <mailto:wind at climate.gsfc.nasa.gov>
> 
> Code 613.2, Climate and Radiation
> 
> SSAI, Inc.
> 
> NASA/GSFC
> 
> Greenbelt, MD 20771
> 
> 
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