Custom Maps for Montana

[ignatz72]

Anyone have a fool-proof methodology for getting good looking custom maps onto the Montana? I worked for 5 hours yesterday and came up with one decent one, and failed with another...

I know the process as Garmin explains it using Google Earth (which is simple enough), but it's getting the custom map at the best possible resolution that seems to elude me. Understood that the final quality will depend heavily upon the quality of the original map (that's why the one that failed did so, it's unreadable on the device as the original is pretty crummy).

I am using Graphic Converter (poor man's Photoshop), and I'm hoping someone else has import/export settings that strike a good balance between file size and quality resolution. I've tried 110ppi up to 150ppi on the import and all manner of JPEG options on the export (baseline, progressive, 4:4:4, 4:2:2, 4:1:1, etc., ad nauseum) to try to keep the file size under the limit (which I've found to be around 3.2MB).

Below is an example of a map I imported yesterday, in JPEG form it appears to be fine quality but once I import to the device as a KMZ it doesn't look so great. Is this just a limitation of the device, or a limit imposed due to the ridiculously small file size restriction? You can only make a 3MB JPEG look so good, in other words.

I'm starting to think the custom maps "feature" is just a gimmick...

Thanks in advance.

[DRTBYK]

Originally Posted by ignatz72

Anyone have a fool-proof methodology for getting good looking custom maps onto the Montana? I worked for 5 hours yesterday and came up with one decent one, and failed with another...

I know the process as Garmin explains it using Google Earth (which is simple enough), but it's getting the custom map at the best possible resolution that seems to elude me. Understood that the final quality will depend heavily upon the quality of the original map (that's why the one that failed did so, it's unreadable on the device as the original is pretty crummy).

I am using Graphic Converter (poor man's Photoshop), and I'm hoping someone else has import/export settings that strike a good balance between file size and quality resolution. I've tried 110ppi up to 150ppi on the import and all manner of JPEG options on the export (baseline, progressive, 4:4:4, 4:2:2, 4:1:1, etc., ad nauseum) to try to keep the file size under the limit (which I've found to be around 3.2MB).

Below is an example of a map I imported yesterday, in JPEG form it appears to be fine quality but once I import to the device as a KMZ it doesn't look so great. Is this just a limitation of the device, or a limit imposed due to the ridiculously small file size restriction? You can only make a 3MB JPEG look so good, in other words.

I'm starting to think the custom maps "feature" is just a gimmick...

Thanks in advance.

I'm certainly no expert as I've only done a few CustomMaps but a couple of points I see right off. You can only use simple JPG images: no progressive. Also, you are trying to use a single image to cover a large area. This will most certainly yield very poor quality when rendered on the GPS. You can still cover the same area but use multiple images of higher resolution. They will be assembled as you geolocate them in GE and then save them to KMZ. Makes for a much faster map draw on the GPS as well. You still have to manage the file size and the number of segments (images) and each images data size to stay under the maximums. There are some very good third-party write ups on Garmin CustomMaps if you Google correctly - sorry, I don't have them bookmarked. If you haven't been there, a good place to start is Garmin Forums

Cheers,

[ignatz72]

Terrific idea on breaking the image up, Makes good sense. Multiple images with the same file size limit would reduce artifacting, for sure.

I'll also give the compression mthod a second look.

Anyone know the display resolution of the Montana? I think the Oregon had 150ppi?

I couldn't see the forest for the trees after my initial testing.

Thansk DB.

[ignatz72]

Thanks again, DRTBYK, that did the trick. Quite a bit more work to stitch together more JPEGs, but much better quality and smaller file size (even lossless) when splitting them up.

[Jan from Finland]

Custom map size must be less than a million pixels. About 1024 x1024 is the max size without compression.

To All: Is there any software which can split a bigger kmz-file into 1024 x 1024 pixel tiles automatically? It would make custom map making less labor intensive.

[ignatz72]

Yep I've since learned that 3.1MB is the disk size limit (Garmin will not be changing this), and resolution limit is 1 Megapixel (@150-155ppi).

Graphic Converter on the Mac has a splitting mechanism that I've been using to divide up my large maps into 4x3 or 3x3, etc. sections. Works well. GC also has a plethora of customizable batch conversion processes that could do splitting and resolution all at once, but I have yet to tackle that. Best part is, GC is only $40 and lets you fully try it, unrestricted, before buying. True Shareware at it's best.

Sorry, I don't know of a PC equivalent.