google map tile creation & cutting with GrADS

[Pablo Romero]

Does anyone have any experience/knowledge of how to create google map tiles using GrADS?
Im currently working on a project that will require this, and Im having trouble with creating accurate image tiles with GrADS, here are some issues...
 
1) setting 'set mproj scaled' causes the entire plot area to be filled (this is desired/good, since I want ONLY the plot area visible in the output, and no gaps, no margins for axes, etc.), but calling 'printim' leaves a 1 pixel border/boundary around the image thats produced (this is not good, the images need to be seemless when placed alongside each other). is this '1 pixel gap' a limitation of printim or of how the plotting area gets filled when setting 'mproj scaled'?
 
2) areas where my grid is undefined produce tiles with the GrADS built-in "ENTIRE GRID UNDEFINED" message in the middle. is there a way to avoid this message, or at least change the color of the font for this message, so that I can set that color to transparent in the resultant png image (through printim)?
 
3)google mapping question: *if* anyone has experience with map tile creation for google maps, can you please point me in the direction of a reference on how to derive the correct lat&lon boundaries for each tile at a given zoom level? Apparently there is a specific equation/method necessary for finding the dimensions of each tile in the google maps mercator projection.
 
Hope this question isnt too far off the topic of GrADS, but I do believe it is related, and any feedback might benefit others in future projects that also utilize google maps.
Thanks in advance,
P.Romero
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