GPSrChive Discussion Forum

A transparent map has display priority over other maps, objects contained in the map are not obscured by detailed maps.

Objects contained in a transparent map will be displayed against the background of any map.

The map in the kmz file will obscure the detailed map but is partially transparent, allowing the visibility of roads from the vector map.

I'll explain: the name entered in the search engine will lead to the Forest Service U.S. Department of Agriculture.

Map sheets have a grid and coordinates marked on the edges of the sheet. I mark points on the map image and assign them the appropriate data. The program creates an additional file containing geographic data – this is calibration (adding georeferenced data to the map).

There are (were) free map creation programs available, such as kmz and jnx. I'm not sure about availability at the moment. I often use MAPC2MAPCNET, but that's not the only program.

To familiarize yourself with how the kmz map and the transparent map work, I've prepared some map "snapshots" for you.

Place the img file in the Garmin folder on the card, enable the detailed map and the Courthouse.img map.

Place the kmz file in the (created CustomMaps folder in the Garmin folder on the card.
In both cases, select the location of Courthouse Montani. on the screen.

Spoiler

Courthouse - Clipping.zip

OK, this is complicated. After copying the files you posted onto my 66i, I was able to see a low-resolution map; it's only visible at displayed scales of 500 ft and above, and only really usuable at 0.3 mi and above. Is that the limit of these maps, or can resolution be finer? If not I'd have to pass on this.

Other observations:
- I viewed with just .img, then just .kmz I see that .img has only trails & but provides the listed name in the Custom Maps menu, while .kmz has no menu listing, and is the detailed base map.
- The trails show up as a thin light blue, same as all the waterways and thus are very hard to distinguish from backgrounds. Zooming out they become nearly invisible. This is true for each base map I have (TopoActive, several OSM alternatives).

I'm afraid that your instructions for "name entered in the search engine will lead to the Forest Service U.S. Department of Agriculture" are not helpful. After a couple of searches I was able to find a site for "FSTopo Map Products". But there are other sites available, and a large number of products. Without a couple of specific web links I don't know where you get your maps.

Finally, I found MAPC2MAPC, and would be glad to give that a try - but I'll need some useful downloads first.

The display method isn't a problem. I can change the color and width of the lines, and I can use the standard "Arterial Road" line display, which will make the line wider.

Spoiler

Courthouse M R.zip

The kmz map should be on the list. After installing the map, a new "Custom Maps" item should appear on the "Configure Map" screen, where you'll find the list of kmz maps.

In the initial phase, the kmz map may be blurry. I think this is what you meant by low resolution.

In the Oregon 650, a map from the same file with the "Normal" map detail level displays from a zoom of 5 km. In the vertical position, I have an area of ​​approximately 15x6 km displayed on the screen.

Check the map detail level and change it to a higher one if necessary.

The kmz map is designed so that at zoom levels of 20 or 10 km, the vector map is displayed, and after zooming to 5 km, the vector map is replaced by the kmz map. The program that creates the kmz map selects the display zoom level depending on the raster map scale.

The free version of MAPC2MAPCNET will create a kmz file, but the map will be covered with an X grid.

I downloaded the maps a while ago, and I think they're still available; I'll look for the link.

Minor note: I did not rename the map file, delete the previous version of the file from your disk.

I'm attaching an image of the display at various zoom levels on an Oregon 650T device with the "Map Detail"
setting set to "Normal."

Spoiler

1 5km.jpg

riogrande wrote: Tue Aug 26, 2025 11:03 pm
- The trails show up as a thin light blue, same as all the waterways and thus are very hard to distinguish from backgrounds. Zooming out they become nearly invisible.

Devices vary in how they display objects due to software and screen resolution. Perhaps the 66i model should have a wider trail line.

Changed:
Trail map - trail line width is 6 pixels, the previous version was 3 pixels wide.

Spoiler

Courthouse M_6 pix.zip

I checked the kmz map again without displaying the vector map. I downloaded the file posted on the forum. In Oregon, the map appears at a zoom level of 8 kilometers.

Spoiler

1.jpg

Your last example at 6 px resolution is good - trails are wide orange dashed line visible at all scales down to 20 feet, and against the backgrounds.
At this point I still need a link to the Forest Service map downloads so I can make my own. For now only the trails, as in this latest .img.

I see that the topic has been exhausted.

I know. You might have reservations about the map's readability, but that was secondary. Until now, there was a technical issue to solve.

I didn't pay attention to the image quality; the map requires graphical correction to make the trail lines and numbering easier to read.

Attached is the image after a minor correction.

Spoiler

Attached is the image after a minor correction.

5743.bmp

The trails come from a file that appears to contain data on trail routes in all parks in the continental United States.

I had trouble creating an .img file of such a large area. I separated the area between the meridian 120° W and 100° W, but that didn't help. I divided the area into four parts and created an .img file from each part. Finally, I combined the four .img files into one.

I want to emphasize the close correspondence between the trail routes on the raster map and the vector data.

riogrande wrote: Thu Aug 28, 2025 8:17 pm Your last example at 6 px resolution is good - trails are wide orange dashed line visible at all scales down to 20 feet, and against the backgrounds.

In fact, a wide trail line is not a good solution, the line should be optimal, a wide trail line may obscure the path line.

This problem can be solved by moving the trail line away from the path, but if the path runs between a slope and a stream, there's no room to move the trail line.

In my experience, I've encountered a trail that partially runs through the middle of a stream. In this case, the trail line obscured the stream, meaning the navigation information was incomplete.

A hiker won't be prepared for this situation based on navigation information.
It's possible to get their shoes wet, and stepping barefoot on sharp rocks is also unsafe.

The trail map I provided is incomplete; it only covers part of the area. Due to file size limitations, I couldn't include a map with full trail coverage in the post.

riogrande wrote: Tue Aug 26, 2025 11:03 pm OK, this is complicated. After copying the files you posted onto my 66i, I was able to see a low-resolution map; it's only visible at displayed scales of 500 ft and above, and only really usuable at 0.3 mi and above. Is that the limit of these maps, or can resolution be finer? If not I'd have to pass on this.

As mentioned earlier, the zoom of the kmz map display depends on the scale of the map and likely the device.

The previous map used is at a scale of 1: 158,4, now I used a map at a scale of 1: 63,3, the zoom was changed by the program from 8 km to 2 km when displaying the kmz map in the same device.


Map at a scale of 1:63,3

Spoiler

Zoom.jpg