HiRise Image Orientation?, What does it mean when North is not at 0 degrees? Options

[Bobby Richardson]

HI everyone.

I've been following MSL's meanderings since Day One, but I still find myself going to HiRise.

I just realized that on the HiRise image info pages they list the map-projected & non-map projected North Azimuth at some angle other than 0 degrees; e.g., 'Map Projected North Azimuth - 274'. 'Non Map Projected North Azimuth - 103' And yet, when I overlay either HiRise image on Goggle Mars, a line drawn parallel to the sides of the imaged surface will extend up to the North Pole.

Does this mean that Map Projected North is located toward the left side of the image instead of toward the top, and Non-Map Projected North is toward the right side of the image? And if so, what's up with the GM overlay?

I hate to bother ya'll if this is a really 'duh' question, but my google-fu just isn't as strong as I thought it was.

TIA
Bobby R.

[JohnVV]

it has been a very long time since i used the Jpg2000 images
i grab the PSD img files and combine the columns

the lat and long of the jpg2000 images should be for the CENTER pixel
and the N azimuth ( as phil stated) is relative to the rows of pixels ( scan lines)


the mapped image is in "Equirectangular" format while the NON mapped should be loosely a "Orthographic" ( with camera tilt) projection

from 45 N to 45 S this will not make much of a difference in the two if the spacecraft is not too tilted off the center ( looking directly down)

the ground track for HIRISE is small enough that there will not be to much warping do to mapping ( unless near a pole and using simplecylindrical )