Custom Map size

[hoytvtecmach]

I am making a Custom Map on Google Earth for a Garmin 62S. The actual size is 6.5 miles by 9.5 miles = 62 sq. miles. The JPEG/ KMZ file size is 123 KB . Is this too big for a Garmin Custom Map ? I have lots of room on the SD card.

[+Team Periwinkle]

Not at all, I have one that is over 32,000 Kb

 

I'm confused. Are you suggesting you have a KMZ file with a single tile, 32 MB in size, that works on a 62s? I don't think that is possible. Or does your 32 MB KMZ have multiple tiles? That would be fine.

 

As stated by Garmin, for all their KMZ-compatible devices, they only support tiles that are 1 MB in dimensions. That usaully means one JPG that is 1024 by 1024 pixels (although it could be any combination - you could do 2048 x 512 pixels or some other combination that multiplies out to 1,048,576 pixels).

 

You can create a KMZ file that has multiple tiles, where each tile is limited to 1 MB. And the number of tiles in the KMZ is only limited by the number of tiles supported by the device (100 tiles for most GPSr, 500 for the Montana series).

 

Reference: https://support.garmin.com/support/searchSupport/case.faces?caseId=%7B9eb27dc0-6377-11df-f5aa-000000000000%7D

Note: Garmin says that images larger than 1024 x 1024 are 'rendered at reduced resolution.' As far as I can tell, this is incorrect - they are not rendered at all. There are various threads that support this finding.

 

To the original poster: the bottom line for you is that yes, your 62 sq. mile KMZ will work fine, as long as the image is less than 1024 by 1024 pixels. And since you are stating that the KMZ file size is 123 Kb, it must be less than 1 MB, since the zip-based compression of a KMZ file isn't good enough to get a 1 MB file down to 123 Kb. So it looks like you're good to go.

 

As the astute reader will realize, the restriction on a 1 MB JPG image with no limit on the actual area covered means that the pixels per mile (or foot, or meter, or whatever) is completely variable when creating KMZ files. This, along with the native resolution of the original image you are using to create the KMZ means that there is NO WAY to predict what will look good when converted to 1024 x 1024 pixel tiles for a KMZ. For a good example, see the bottom of this page, where I have an example of one map with two different 'number of tiles.'

http://www.gpsfiledepot.com/maps/view/574/

 

I have some KMZ maps that cover thousands of acres with one tile and look fine. And some cover barely a few hundred acres but need to be broken up into multiple tiles to retain adequate / readable resolution.

 

Regards

 

Dave