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Map Management 201
In Map Management 101, we covered the basics of how the PN-40 determines how a map should be displayed. This section we will expand on the ideas learned in 101.
Creating Map Packages
Lets say you want to cut CDOQQ, SAT10, USGS Quad, and a NOAA Harbor Chart for a given area:
- Should you cut each map data type separately, creating 4 separate map packages each containing one map type.
- SeparatelyColor-CDOQQ-Map.pm0
- SeparatelySat10-SAT10-Map.pm0
- SeparatelyQuad-3DTQ-Map,pm0
- SeparatelyChart-NOAAH-Map.pm0
- or, Should you cut them all at one time, creating 1 map package containing 4 map data types.
- Together-CDOQQ-Map.pm0
- Together-SAT10-Map.pm0
- Together-3DTQ-Map.pm0
- Together-NOAAH-Map.pm0
Cutting Separately
- As each map file would have a unique filename, each map file would be listed on the Data Management page. This would allow each map file to be enabled or disabled separately from the others. This provides the greatest flexibility.
- As each map file is listed separately, the list on the Data Management page can become quite long. If you don't like a long list, then cut them together at the loss of some flexibility.
- If the area being cut is different for each map type, then they must be cut separately.
Cutting Together:
- All maps within the package are enabled or disabled by one selection in the Data Management page.
- As all data types are listed under one map package, the list on the Data Management page stays shorter.
- Can only be cut together if area being cut is exactly the same for each map type.
How the name of the Map File is used by the PN-40
In previous sections, we learned that when TopoUSA (or XMap) creates/cuts a map, the filename of the resulting Map File has the following structure:
- xxxxxxxx-yyyyyy-Map.pm0
Where:
- 'xxxxxxx' is the name entered when you pressed the "Save" button.
- 'yyyyy' is the Map Type (i.e., SAT10, CDOQQ, DOQQ, 3DTQ, etc), added automatically by TopoUSA
- 'Map' is added automatically by TopoUSA
So, what happens if we were to manually change the filename before transferring it to the PN-40? Is there reason why we might want to change the filename?
Manually Changing the Name
Here are the results I found from manually changing the filename of a Map File.
| From | To | Result |
|---|---|---|
| test-CDOQQ-Map.pm0 | test-CDOQQ-Map.xxx | Changing the file extension to something other than PM0 prevents the file from being displayed. The PN-40 is only looking for files with the extension of PM0. |
| test-CDOQQ-Map.pm0 | test1-CDOQQ-Map.pm0 | In this example, the first part of the name has been changed. This would result in the file being moved from the 'test' map package to the 'test1' map package. |
| test-CDOQQ-Map.pm0 | test-xxxx-Map.pm0 | In this example, the middle part of the name is changed. As the middle part of the name isn't used by the PN-40 to determine the map type, everything would function the same. You would notice no changes within the PN-40. |
| test-CDOQQ-Map.pm0 | test-xxxxx.pm0 | In this example, two changes were made. The middle of the filename was changed and the '-Map' was completely dropped from the name. You would notice no changes within the PN-40. If '-Map' is removed from the filename, then the PN-40 will list the name of the map package using only the first part of the name. |
| test-CDOQQ-Map.pm0 | test-CDOQQ-xxx.pm0 | This example will cause a slight change in the PN-40. Changing 'Map' to anything other than 'Map' will cause the first and middle part of the name to appear in the Data Management page. So, on the Data Management page, the map package would go from 'test' to 'test-CDOQQ'. |
| test-CDOQQ-Map.pm0 | test.pm0 | This example will cause a slight change in the PN-40. By dropping both the data type (middle part) and 'Map', the PN-40 will display this as 'TEST' in the Data Management page. |
Why change the Name?
Let's start with an example:
I like to have a DRAW layer of every ride that my wife and I have been on. To control this data separately from all other map data, I select only the Draw Layers on the Option->Handheld page before cutting the data. As I also want this data to be displayed at any zoom level, I set the zoom range to 1-17. Now I start selecting grids to cut. This is where I ran into a problem!
While we normally ride here in Central Oregon, we also have ridden on the coast and in eastern Oregon. The problem is, TopoUSA doesn't allow me to select all these places at one time. I get the "The Map Package cannot be saved. The selected datasets exceed map capacity" message. So, to cut maps of everyplace we've ridden, I had to make 5 separate cuts:
- Trails1-DRAW-Map.pm0
- Trails2-DRAW-Map.pm0
- Trails3-DRAW-Map.pm0
- Trails4-DRAW-Map.pm0
- Trails5-DRAW-Map.pm0
This results in five entries on the Data Managment page. Now, to enable or disable this data, I have to check/uncheck all five map packages. But, if I change the name of the files to:
- Trails-DRAW1-Map.pm0
- Trails-DRAW2-Map.pm0
- Trails-DRAW3-Map.pm0
- Trails-DRAW4-Map.pm0
- Trails-DRAW5-Map.pm0
Now, all five files will become part of the map package 'Trails'. This results in one entry in the Data Management page. Now, to enable or disable the data, I only have to check/uncheck one item.
Here are the results I found from manually changing the filename of a Map File:
| From | Data Management | Results |
|---|---|---|
| Trails1-DRAW-Map1.pm0
Trails1-DRAW-Map2.pm0 | Trails1-DRAW | In this example, I changed "-Map" by adding a number. This causes the name shown in Data Management to include "-DRAW" in the name displayed. But, as can be seen, the two files have been combined into one Map Package. |
| Trails5-DRAW1-Map.pm0
Trails5-DRAW2-Map.pm0 | Trails5 | In this example, I changed the map type (i.e., "DRAW") by adding a number. Unlike in the example above, the name is shown without the map type. But, like the example above, the two files have been combined into one Map Package. |
| Trails6-DRAW1-Map1.pm0
Trails6-DRAW1-Map2.pm0 | Trails6-DRAW1 | The results of this example are similar to the first example, in that the map type (i.e., "-DRAW1") is displayed in Data Management. In this example, I added a number to both "-DRAW' and "-Map". |
| Trails9-DRAW1-Map1.pm0
Trails9-DRAW1-Map2.pm0 Trails9-DRAW2-Map1.pm0 Trails9-DRAW2-Map2.pm0 | Trails9-DRAW1
Trails9-DRAW2 | This example farther shows how map files are combined into Map Packages when the filenames are changed. |
| Trails2a.pm0
Trails2b.pm0 | Trails2a
Trails2b | File are not combined. |
| Trails3-1.pm0
Trails3-2.pm0 | Trails3 | In this exampe, "-Map" was removed from the filename and the map type was changed to a number. As can be seen, the two files have been combined into one Map Package. |
| Trails4-1-Map.pm0
Trails4-2-Map.pm0 | Trails4 | Files are combined into one Map Package. |
| Trails7-1-1.pm0
Trails7-1-2.pm0 | Trails7-1 | Files are combined into one Map Package. |
| Trails8-1-1.pm0
Trails8-2-1.pm0 | Trails8-1
Trails8-2 | File are not combined. |
