Merging OSM maps using GMAPTOOL

[Grispoil61]

I am getting unexpected results when merging a couple of maps obtained from the bbbike dot org website:

Spoiler

https://extract.bbbike.org/

I am downloading 2 maps covering the SAME area to create a 3rd map, a TOPO map, the first map is of type 'Garmin Leisure (latin1)' and the second map is of type 'SRTM World Contours Garmin (40m)'. When I merge them together using GMAPTOOL using the defaults options, I am getting strange results when dealing with rivers. See the attached pictures to compare, you will note that in the merged map, the river is shown as a small line instead of it's real size.

Spoiler

BBIKE OSM Leisure.jpg

Spoiler

BBIKE OSM Leisure + SRTM.jpg

Any idea on what is causing this and how to correct this?

Thanks for your expertise in this area.

[987]

Hi.
I have not used those maps in particular, so anyone correct me if a am wrong.
In general, you cannot take two ready-made maps to produce a third. It has to do with how they are generated and you would need to combine the information at an earlier stage of the process.

With that said, did you try loading both those two maps onto your device, without trying to combine them?
Map makers often make sure to set parameters that will decide which map is drawn on top, meaning that contours typically should be drawn highest and the rest is transparent.

[LostAgain]

Might be a .typ file issue with the combined map?
The .typ used in the finished product might have different display parameters for polylines, polygons etc. than the .typ used for the original.
What 987 suggests usually works ok too.

[GPSrChive]

First, extract the TYP file from each of the maps you are combining, then compare them to determine which one uses the desired element.

Next, extract the TYP file from the combined map and replace the desired element in the combined map TYP file.

Then, apply the new modified TYP file to the combined map.

I like using TYPwiz for this.

[Grispoil61]

Hi.
I have not used those maps in particular, so anyone correct me if a am wrong.
In general, you cannot take two ready-made maps to produce a third. It has to do with how they are generated and you would need to combine the information at an earlier stage of the process.

With that said, did you try loading both those two maps onto your device, without trying to combine them?
Map makers often make sure to set parameters that will decide which map is drawn on top, meaning that contours typically should be drawn highest and the rest is transparent.

I have been playing with this a bit and it looks like you are correct, these two maps are not really meant to work together. On my GPS, an Oregon 700, using two distinct maps, I get the same problem, however, I have noticed that the river display is correct at around the 5km zoom level and out but, if I zoom in, I get the 'thin' rivers. If I disable the contour map on my GPS, the display is good regardless on zoom level. The reason I combine them is to be able to use the same map with contours in both my GPS and basecamp.

First, extract the TYP file from each of the maps you are combining, then compare them to determine which one uses the desired element.

Next, extract the TYP file from the combined map and replace the desired element in the combined map TYP file.

Then, apply the new modified TYP file to the combined map.

I like using TYPwiz for this.

I have downloaded TYPwiz and played with it a bit, however, this is way too much involved for my needs. I just need a topo maps that I can use on my GPS and Basecamp that I can update easily every few months. I have seen other 'ready to go' topo maps, however, I do not like their color scheme. I understand that TYPwiz can probably help me here, however, this seems too much involved for me at this time.

I have also downloaded a contours map from here:

Spoiler

https://garmin.opentopomap.org/

and merged it with the BBBike one and it seems to be working better. Still playing with it, however, I think I am all set now.

Thanks for your suggestions and help.

[Przekątny]

I have been playing with this a bit and it looks like you are correct, these two maps are not really meant to work together. On my GPS, an Oregon 700, using two distinct maps, I get the same problem, however, I have noticed that the river display is correct at around the 5km zoom level and out but, if I zoom in, I get the 'thin' rivers. If I disable the contour map on my GPS, the display is good regardless on zoom level. The reason I combine them is to be able to use the same map with contours in both my GPS and basecamp.

The contour map can be improved, one way is to remove the 0x003a object from the .img file,
this object obscures the detailed map.