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When plotting the grid (Function->Grid) on OCTS chlorophyll images, I have noticed that the grid is somewhat shifted relative to the position it is supposed to be. If, for example, one chooses to load the part of the image that corresponds to Portugal, one gets an image of the Atlantic ocean because the grid is shifted to the left and a bit upwards. I have tried to compensate for this discrepancy by adding or extracting from the coordinates I use when loading the image, but it is not clear how much the grid is shifted from its correct position.
Am I doing something wrong? Can anyone suggest what could be done?
I've not been able to replicate the problem you see.
Could you provide an example filename and coordinates you used?
I have encountered the error in the following files: O19970651997072.L3m_8D_CHL_chlor_a_9km, O19970731997080.L3m_8D_CHL_chlor_a_9km and O19970811997088.L3m_8D_CHL_chlor_a_9km.
The coordinates I used were:
Lat range (N/S): 42.05 34.96
Lon range (W/E): -11.1 -4.96
The error becomes clear when I compare the above images to the respective full images after having plotted the grid (Function -> Grid). In case that helps you, what I see is that the Prime Meridian (International or Greenwich Meridian, longitude 0°) does not pass through Greenwich (or anywhere near the United Kingdom), but passes just off the Atlantic coast of Portugal (see [img][/img]). There is also a smaller shift in the latitude of the grid.
OK, with OCTS SMI files, I can replicate the problem. The good news is the solution is relatively simple.
The bad news is - won't work for the embedded IDL license - the runtime version needs to be rebuilt after
a modification to the sdp_load_socts.pro file has been made.
The problem arose when we changed the definition of the SMI files. Originally, the files were 4096x2048
pixels. To resolve a sampling problem, the SMI files are now 4320x2160. The code that reads the OCTS
SMI files wasn't updated to reflect this change.