First I would like to note that I have no idea wether my employer would be intereseted or not but I wanted to test the waters on this subject before presenting them even with this scenerio. I would also like to apologize if this is the wrong place for such a discussion but I was unsure where else to go.
We need to bring in TIFFs with an associated TFW (TIF World File) and
then bring in either DXF or draw vectors in the Gfig plugin and use
these vectors as a mask(clip/crop) and write out a new image and new TFW.
We need the option of using DXF and/or the gfig plugin.
For those not familiar with them a TFW file contains georefencing
information (real world coordinates etc) such as your Easting and
Northing along with what each pixel is in real ground coordinates along
with to rotation fields.
This URL describes the TFW format:
To give a better idea of what I mean by all this here is an hypothetical
Say you have an aerial picture of the some city that covers the
coordinates of 1000 East to 10000 West and 1000 North to 10000 South.
Now you want to chop out an area of this photo though that covers an
odd shaped boundary. It could be 3 vertices or 500. This boundary is in
a dxf file so you import it. Then clip/mask the image to this boundary.
Chances are your outer most coordinates have now changed. That is, your
most extreme East, West, North and South coordinates may have dropped
several thousand each. You now need to not only save this raster file
but along with it write out a TFW file which is simply and ascii file
with the new coordinates to correctly reference the raster within a
Having said that I really do not know what all would be involved with
doing this. I do know there is software out there for AutoCAD that will
do this but it is not only pricey but works only in windows and is
priced PER seat. We dont need half the things they do either. We simply
need a method of cliping to geographic vectors. I would like to hear
anyones views on this and perhaps even ballpark estimates as to how much
the cost to develope such a beast would be and approximately how much
time it might take. Yes, cost. I am not asking someone to develope this
for free. My plan is to find out how much someone would charge for it
and present the idea to my employer. I would also present it to them
with the idea that the plugin remain fully GPL.
Jason M. Nielsen
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