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Map Management 101
One of the great features of the PN-40 is it's ability to display all types of Map Files. But, after loading all these Map Files into either the Internal Memory of the PN-40 or on to the SD card, how does the PN-40 determine which Map File should be displayed?
Hopefully, this page will give you an understanding of how the PN-40 makes this decision.
For those who like a visual/auditory demonstration, many of the things explained on this page are available in a presentation authored by DrNature of the DeLorme forums. A YouTube video created by DeLorme forum member TotemLake also offers instruction on cutting map file packages from TopoUSA and transferring them to the PN-40.
What is a Map File?
A Map File is a file created by TopoUSA (or XMap) during the "cutting" process. The file extension of a Map File is always PM0. The "cutting" process is used to convert the image/map information stored on your hard drive (in a format that can only be used by TopoUSA/XMap) into a format that can be used by the PN-40. For information on how to create or "cut" a map, see Cutting Map Packages. For information on how to download different types of images/maps, see Selecting Imagery and Downloading Imagery.
When TopoUSA (or XMap) creates/cuts a map, the filename of the resulting Map File has the following structure:
- xxxxxxxx-yyyyyy-Map.pm0
Where:
- 'xxxxxxxx ' is the name you used when you created the map file and is used as the Map Package name.
- 'yyyyyy' - Automatically added by TopoUSA based on the type of data contained within the map file.
- TP7 - Topo USA 7.0 Data Series
- TP8 - Topo USA 8.0 Data Series
- DRAW - Draw Layer
- DOQQ - Aerial Imagery (Black and White)
- CDOQQ - Aerial Imagery (Color)
- SAT10 - Satellite Imagery
- IREG - ImageData Series (created by XMap)
- CUSTRAS - XMap Raster Data Snapshot
- CUSTVEC - XMap Vector Data Snapshot
- XTP07 - XMap USA Topographic Data 2007
- XTP08 - XMap USA Topographic Data 2008
- NOAAG - NOAA General Charts
- NOAAH - NOAA Harbor Charts
- NOAAHI - NOAA Harbor Inset Charts
- NOAAHD - NOAA Harbor Detailed Charts
- 'Map' - Automatically added by TopoUSA.
- 'pm0' - Automatically added by TopoUSA.
NOTE: These files are stored in the 'DeLorme Docs/Mobile Maps' folder on your hard drive.
Using the Map Files
Now that we have created the Map Files, they must be stored (transferred) into either the Internal Memory of the PN-40 or onto a SD card. There are several ways to transfer the Map Files:
Data Exchange Mode
This is the mode that the PN-40 defaults to when first connected to the PC. In this mode, you can use the Exchange Wizard to transfer your Map Files to either the Internal Memory or the SD card (if installed). BE WARNED: Transferring map files using this mode is EXTREMELY SLOW!! Normally, you would only want to use this mode for transferring waypoints, routes, tracks, and geocaches.
Map Transfer Mode
While you can use the Data Exchange Mode to transfer maps to the PN-40, you should really use the Map Transfer Mode. After selecting this mode, your next choice is "Transfer to SD" or "Transfer to Internal". Once you select, a removeable drive will be created. At this point, you can use the Exchange Wizard of TopoUSA or Windows Explorer to transfer the Map files.
SD Card Reader
If want the fastest possible transfer rate, then purchase a SD card reader. Place the SD card into the Card Reader and then use Windows Explorer to transfer the Map Files to the SD card. Once all the map files have been transferred, insert the SD card into the PN-40.
NOTE: To transfer map files to the Internal Memory of the PN-40, either Data Exchange Mode or Map Transfer Mode->Transfer to Internal must be used. But, again, the best choice is using Map Transfer Mode.
NOTE: If using Windows Explorer to transfer the maps files to either Internal Memory or the SD card. Be sure the files are placed into the 'maps' folder. When using the Exchange Wizard of TopoUSA, it will always place the files into the 'maps' folder.
Logic used by PN-40
Disclaimer: While the steps below are not exact, as I have no access to the source code, they should describe the general logic used by the PN-40 to determine which Map File will be displayed.
Now that you have all these Map Files stored, how does the PN-40 use them. The following steps are used by the PN-40 to determine which Map File to display:
- Create a list of all Map Files in Internal Memory and on the SD card (all files with a file extension of PM0). This also includes the built-in base map and regional maps.
- Eliminate all Map Files that have been disabled in Data Management.
- Eliminate all Map Files that have been disabled in Data Layering.
- Eliminate all Map Files that are outside of the current zoom range.
- Eliminate all Map Files that are outside of the current map view.
- Of the Map Files remaining, look for a Map File with the highest priority type.
- If more than one Map File, choose the one with the newest file Date/Time stamp.
- Display the Map File. If no Map Files are left, display nothing..
Exceptions to above logic
Normally, only one Map File will be displayed. The exceptions are:
- An enabled DRAW Map File is overlaid onto all other map types. But only if Draw Layers is set to a higher priority in Data Layering.
- If "Show Hybrid Map" is selected in Map Setup, and there is an enabled Topo USA Data Series Map File, and the current zoom range is 13-17, then the TopoUSA map data will be overlaid over any other Map File.
- If the Map File with the highest enabled priority only covers part of the current map view, then the Map File with the next lower enabled priority will be displayed in the remaining portion of the display.
Step 1 - Creating the lists
During power-up, the PN-40 creates three lists:
- A list of all Map Files,
- A list of Map Packages, and
- A list of Map Types (i.e., DOQQ, CDOQQ, 3DTQ, SAT10, etc)
The Map Files list is a list of all files stored in internal memory or on the SD card with a file extenstion of PM0.
The Map Package list is generated based on the filename of the Map files. The first part of the filename (the 'xxxxxxx' as shown above) is used to generate the Map Package list. This list is displayed on the Data Management page.
The PN-40 generates the Map Types list by reading the Header information from each Map File. Within this Header is the map type. The zoom range of the Map File is also stored within the Header, which is used during step 4. NOTE: Even though TopoUSA/XMap stores the map type as part of the filename (the 'yyyyyy' as shown above), this part of the filename isn't actually used to generate the Map Type list.
Example: Lets say the following files are stored in either Internal Memory or on the SD card:
- BigSummit-IREG-Map.pm0
- CentralOregon-3DTQ-Map.pm0
- CentralOregon-DOQQ-Map.pm0
- Home-DOQQ-Map.pm0
- IdahoSA-TP7-con.ybr
- IdahoSA-TP7-Map.pm0
- Oregon-3DTQ-Map.pm0
- OregonSA-TP7-con.ybr
- OregonSA-TP7-Map.pm0
- SarTraining-3DTQ-Map.pm0
- SarTraining-CDOQQ-Map.pm0
- SarTraining-SAT10-Map.pm0
- Sisters-IREG-Map.pm0
- TrailRides-DRAW-Map.pm0
- WashingtonSA-TP7-con.ybr
- WashingtonSA-TP7-Map.pm0
This will create the following three lists:
| List of Map Files | List of Map Packages | List of Map Types |
|---|---|---|
* BigSummit-IREG-Map.pm0
| * BigSummit
| * Draw Layers
|
Step 2 - Data Management
This page lists the name of all your map packages loaded into the internal memory of the PN-40 and on the SD card. The Data Management page is used to control which map packages are enabled or disabled. If a map package has been disabled (no checkmark), then all Map Files within the map package will be disabled. Only map packages that are enabled can be displayed by the PN-40.
Example: If SarTraining is disabled on the Data Management page, then the following Map Files would be eliminated from being displayed:
- SarTraining-SAT10-Map.pm0
- SarTraining-CDOQQ-Map.pm0
- SarTraining-3DTQ-Map.pm0
This would leave the following Map Files available for display:
- BigSummit-IREG-Map.pm0
- CentralOregon-3DTQ-Map.pm0
- CentralOregon-DOQQ-Map.pm0
- Home-DOQQ-Map.pm0
- IdahoSA-TP7-Map.pm0
- OregonSA-TP7-Map.pm0
- Oregon-3DTQ-Map.pm0
- Sisters-IREG-Map.pm0
- TrailRides-DRAW-Map.pm0
- WashingtonSA-TP7-Map.pm0
Step 3 - Data Layering
Data Layering determines which type of maps files (i.e., DRAW, CDOQQ, 3DTQ, and TP7, etc) you want displayed. The Data Layering page also controls the order that maps types will be displayed. The list is ordered from highest priority (top of list) to lowest priority (bottom of list). Only map types that are enabled can be displayed by the PN-40. See Data Layering for directions on changing the order.
Example: If 3DTQ is disabled on the Data Layering page, then the following Map Files would be eliminated from being displayed:
- CentralOregon-3DTQ-Map.pm0
- Oregon-3DTQ-Map.pm0
This would leave the following Map Files available for display:
- BigSummit-IREG-Map.pm0
- CentralOregon-DOQQ-Map.pm0
- Home-DOQQ-Map.pm0
- IdahoSA-TP7-Map.pm0
- OregonSA-TP7-Map.pm0
- Sisters-IREG-Map.pm0
- TrailRides-DRAW-Map.pm0
- WashingtonSA-TP7-Map.pm0
Step 4 - Zoom Range
When you create/cut a Map File, you also have to select the Zoom Range (Options->Handheld tab in TopoUSA). If the current zoom level (Map Page) is outside of the range that a Map File was cut, then it can not be displayed and is eliminated from the list.
Example: Of the remaining Map Files, lets add the zoom range that was used when the Map Files were cut:
- BigSummit-IREG-Map.pm0 - Cut at a zoom range of 5-14
- CentralOregon-DOQQ-Map.pm0 - Cut at a zoom range of 10-16
- Home-DOQQ-Map.pm0 - Cut at a zoom range of 10-16
- IdahoSA-TP7-Map.pm0 - Cut at a zoom range of 5-17
- OregonSA-TP7-Map.pm0 - Cut at a zome range of 5-17
- Sisters-IREG-Map.pm0 - Cut at a zoom range of 5-13
- TrailRides-DRAW-Map.pm0 - Cut at a zoom range of 1-17
- WashingtonSA-TP7-Map.pm0 - Cut at a zoom range of 5-17
Now, lets say the current zoom level is 14. This would leave the following Map Files available for display:
- BigSummit-IREG-Map.pm0
- CentralOregon-DOQQ-Map.pm0
- Home-DOQQ-Map.pm0
- IdahoSA-TP7-Map.pm0
- OregonSA-TP7-Map.pm0
- TrailRides-DRAW-Map.pm0
- WashingtonSA-TP7-Map.pm0
Sisters-IREG-Map.pm0 got eliminated because zoom level 14 is outside of 5-13.
Step 5 - Current View
In this step, the PN-40 will eliminate all Map Files that are outside of the current viewing area of the Map Page. If the data within the Map File is an area not currently being displayed on the Map Page, no reason to keep it in the list of Map Files that can be displayed. In the example we've created, lets say all remaining Map Files are within the current viewing area except for IdahoSA-TP7-Map.pm0 and WashingtonSA-TP7-Map.pm0.
Step 6 - Data Layering Priority
Now the ordering of the Map Types on the Data Layering page becomes important. At this point in the logic, the PN-40 must pick the Map File(s) with the highest layering priority.
Example #1: If the ordering on the Data Layering Page is:
* Draw Layers
|
|
Then the TrailRides-DRAW-Map.pm0 file would have the highest priority, and would be displayed. But, because 'Draw Layers' are always drawn "over" other maps, the PN-40 will look for the next highest priority map file, which would be the BigSummit-IREG-Map.pm0 file. So, in this example, data from the BigSummit-IREG-Map.pm0 file would be displayed with the data from the TrailRides-DRAW-Map.pm0 overlaid. And, if 'Show Hybrid Map' is checked, then the data from OregonSA-TP7-Map.pm0 would also be overlaid onto the BigSummit-IREG-Map.pm0 map. See Exceptions above for why.
Example #2: If the ordering on the Data Layering Page is changed to:
- IMAGEREG
- Draw Layers
- COLOR DOQQ
- DOQQ
- 3DTQ
- SAT10
- TOPO USA 7
The same map will be displayed, BigSummit-IREG-Map.pm0 and the Oregon-TP7-Map.pm0 map file will be overlaid if 'Show Hybrid Map' is checked. But, because the Draw Layer is now at a lower priority than the IMAGEREG data, the TrailRides-DRAW-Map.pm0 wouldn't be overlaid.
Example #3: If the ordering on the Data Layering Page is changed to:
- Draw Layers
- DOQQ
- IMAGEREG
- COLOR DOQQ
- 3DTQ
- SAT10
- TOPO USA 7
Then the TrailRides-DRAW-Map.pm0 file would have the highest priority, and would be displayed. But, because 'Draw Layers' are always drawn "over" other maps, the PN-40 will look for the next highest priority map file, which would be the CentralOregon-DOQQ-Map.pm0 file and the Home-DOQQ-Map.pm0 file. Because there are two Map Files of equal priority, we need to go to Step 7 to determine which one will get displayed.
Step 7 - Map File creation Date/Time
If two (or more) Map Files are of equal priority, then the PN-40 will choose the file with the newest file creation date/time.
Example: In Example #3 above, two map files had an equal priority:
- CentralOregon-DOQQ-Map.pm0
- Home-DOQQ-Map.pm0
So, if CentralOregon-DOQQ-Map.pm0 has a newer date/time, then it would be displayed. But, if Home-DOQQ-Map.pm0 has the newest date/time, then it would be displayed.
For more information on Map Packages, see Map Management 201
