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<DIV><FONT size=2>Hi,</FONT></DIV>
<DIV><FONT size=2></FONT> </DIV>
<DIV>Here is the little experience I've been doing with the GCPsToGeoTransform(
)<BR>GDAL function within the OpenEV application</DIV>
<DIV><BR>The extracted GCPs come from a RadarSat Image file.<BR><BR>These are
the GCPs given by :<BR><BR>imgds=gdal.Open( imgfile )<BR>gcps = imgds.GetGCPs(
)<BR><BR>1 (0.50P,0.50L) -> (-135.1095150E,69.8421120N,0.00)<BR>2
(3075.50P,0.50L) -> (-134.6161190E,69.8693480N,0.00)<BR>3 (6150.50P,0.50L)
-> (-134.1211540E,69.8952230N,0.00)<BR>4 (0.50P,2212.50L) ->
(-135.0509610E,69.7197390N,0.00)<BR>5 (3075.50P,2212.50L) ->
(-134.5604000E,69.7469050N,0.00)<BR>6 (6150.50P,2212.50L) ->
(-134.0682890E,69.7727180N,0.00)<BR>7 (0.50P,4424.50L) ->
(-134.9928930E,69.5973540N,0.00)<BR>8 (3075.50P,4424.50L) ->
(-134.5051320E,69.6244510N,0.00)<BR>9 (6150.50P,4424.50L) ->
(-134.0158420E,69.6502040N,0.00)<BR>10 (0.50P,6636.50L) ->
(-134.9353020E,69.4749570N,0.00)<BR>11 (3075.50P,6636.50L) ->
(-134.4503100E,69.5019860N,0.00)<BR>12 (6150.50P,6636.50L) ->
(-133.9638050E,69.5276810N,0.00)<BR>13 (0.50P,8848.50L) ->
(-134.8781810E,69.3525470N,0.00)<BR>14 (3075.50P,8848.50L) ->
(-134.3959230E,69.3795100N,0.00)<BR>15 (6150.50P,8848.50L) ->
(-133.9121720E,69.4051470N,0.00)<BR><BR>Now I want to use the
gdal.GCPsToGeoTransform( ) function to retreive the<BR>Georeferencing
information for these GCPs<BR><BR>First step is to convert the Lat/Longs to UTM
coordinates in the correct<BR>Datum<BR><BR>1 (0.50P,0.50L) ->
(495787.8827608E,7748093.2830998N,0.00)<BR>2 (3075.50P,0.50L) ->
(514745.4777109E,7751173.2278477N,0.00)<BR>3 (6150.50P,0.50L) ->
(533715.4904099E,7754255.2492804N,0.00)<BR>4 (0.50P,2212.50L) ->
(498028.5699152E,7734443.4741512N,0.00)<BR>5 (3075.50P,2212.50L) ->
(516984.0291049E,7737533.2731664N,0.00)<BR>6 (6150.50P,2212.50L) ->
(535951.9736002E,7740625.0613713N,0.00)<BR>7 (0.50P,4424.50L) ->
(500276.5221832E,7720794.6708395N,0.00)<BR>8 (3075.50P,4424.50L) ->
(519229.8898777E,7723894.2612719N,0.00)<BR>9 (6150.50P,4424.50L) ->
(538195.7154961E,7726995.8751202N,0.00)<BR>10 (0.50P,6636.50L) ->
(502531.7368161E,7707146.8528349N,0.00)<BR>11 (3075.50P,6636.50L) ->
(521482.9247313E,7710256.1735550N,0.00)<BR>12 (6150.50P,6636.50L) ->
(540446.7202882E,7713367.6756985N,0.00)<BR>13 (0.50P,8848.50L) ->
(504794.1408911E,7693499.8886254N,0.00)<BR>14 (3075.50P,8848.50L) ->
(523743.2389120E,7696618.9937144N,0.00)<BR>15 (6150.50P,8848.50L) ->
(542704.9250019E,7699740.2243816N,0.00)<BR><BR>then use the
gdal.GCPsToGeoTransform( gcps, 1 ) function to retreive the<BR>calculated
georeferencing data and I always get this<BR><BR>(-1.#IND, -1.#IND, 1.#INF,
-1.#IND, -1.#IND, 1.#INF)<BR><BR>which tends to make me think there is something
wrong with the calculation </DIV>
<DIV>routine or the input parameters are not good (or any other
reason).<BR><BR>But if I choose 3 points in all those (any 3 not aligned) the
function does </DIV>
<DIV>return some data (which I didn't check to see if it was correct or
not)<BR></DIV><FONT size=2>
<DIV>Thank You</DIV>
<DIV> </DIV>
<DIV>David</DIV>
<DIV><BR>________________________________</DIV>
<DIV> </DIV>
<DIV>VPI - Innovative Radar Solutions<BR>________________________________</DIV>
<DIV> </DIV>
<DIV>David Legault, M. Eng.<BR>Signal Processing Specialist,
Programer<BR>Vantage Point International Inc.</FONT></DIV></BODY></HTML>