Need a link to Garmin CustomMap limitations

[Seldom]

Boyd regularly posts these as needed so I'm hoping he can point me to his source.

I just made a KMZ with GM of an area about 9 miles x 3 miles with 1 foot NAIP imagery.  This looks superb in Google Earth, but is a blurry mess in BaseCamp and on my Etrex30.  The KMZ is 73MB.

Thanks.

[Boyd]

I think that is too big. The math is very simple and you only need to remember two specs. Each tile must be no larger than 1024x1024 pixels, and there are a limit of 100 tiles (on every unit but the Montana).

So, at 1 foot per pixel, a grid of 10 tiles x 10 tiles containing 100 tiles total would be 10240 x 10240 pixels, or about approximately 2 miles x 2 miles. The only other published limit I know of is that each tile must be no more than 3MB.

I have never been able to create a usable custom map that is anywhere near 73MB, they tend to be very small files. How did you create the .kmz in GlobalMapper? You can use tiles larger than 1024x1024, but then they will be rendered with low detail, as you describe.

Personally, I use the raster image export for .kmz along with gridding at a fixed 1024x1024 tile size. It can take a couple tries to crop the original image down to the point where it doesn't exceed 100 tiles, but once I figure that out then the maps work well.

Since you asked for a link... here you go https://support.garmin.com/support/searchSupport/case.faces?caseId=%7B9eb27dc0-6377-11df-f5aa-000000000000%7D

[Seldom]

Thanks, Boyd.
The output was a single NAIP screen dump exported as a raster KMZ.  Grid cell size was set to 1024x1024, but I specified no gridding for the output on the gridding tab.  Guess I need to do some experimenting.

[Boyd]

Heh, if you just made one tile with a map of that size and resolution then it would indeed look terrible. You are going to be over the 100 tile limit. Use the Globalmapper feature to resample the map at a lower resolution (the box that says "click here" in the export dialog. You can change the units to feet or meters to get a handle on what works.