Viewing Georeferenced PDFs
In preparation for our Vietnam trip I have downloaded GeoPDFs from:

Presumably, these are georeferenced in some way.

Is there any software that I can view these PDFs on a PC with a GPS to see the current location on the relevant map? It would be good if the software could load the required map automatically as the location moves from sheet to sheet.
OK, not simple but I have found 2 possible ways to do this.

1. OziExplorer

Download OziExplorer.

This procedure may not work with the trial or shareware versions. (The conversion should work but you may not be able to view file so you would have to use the second option.)

I have an OziExplorer licence so that's not a problem for me.

Go to Utilities page.

Image File Conversion

This is a program which allows conversion of various map image formats to GeoTiff.

Download, unzip to a folder and run the ImageConvertOzi.exe program for simple conversions.

Run ImageConvertOzi.exe and point it at the folder containing GeoPDFs.

It creates a subfolder called ozi_converted that contains .tif and .tfw files.

This page explains what to do next:

Importing a Single DRG Map

Select the Import Map/Single DRG Map Option on the File Menu.

Step 1 - Find the image file of the map you want to import.

You need to know the name of the image file of the map you want to import. (It must be one of the supported image types such as TIF, BMP, PNG, JPG, SID, ECW, .....). You will have to find out this name from the information supplied with the CD, I would assume.

Press the OK button and the software will allow you to navigate through your Disk Drives and Directories until you locate the file. If the CD is from the USGS then the file would normally be located in the DATA folder. When you have located the file, select it by double clicking on the name or click on the name and press the Open button.

A METADATA (FGD or other) file may also be available for the image. This is usually located in the METADATA directory of the CD. If you copy the image file to your hard drive the metadata (FGD) file must also be copied and placed in the same directory as the image file.

Step 2 - Specify the Name and Path of the OziExplorer Map file you want to create.

The Map file name will be the same name as the image file but with a .MAP extension. The name of the file can be changed but do not change the extension. Save the file.

Step 3 - The newly created Map will now be opened.

From now on you open the Map by selecting the MAP file using the Load Map from File option. The original image must always be available when opening the map.

The map calibration used can be viewed using the normal Check Calibration of Loaded Map menu option.

There is also a bulk conversion procedure.

I have converted one file and it loads into OziExplorer.

When I use File, Check Calibration it shows calibration markers on top left and bottom right of sheet which are on white borders of paper sheet. Who knows whether it is calibrated correctly.

Another problem is that the .pdf file was 12Mb while the .tif file is 44Mb.

2. Avenza

This page explains that if you add the .tif and .tfw files created by ImageConvertOzi.exe to a .zip file they can be loaded into Avenza on Android, iOS and Windows devices. I haven't tried this.

Any suggestions of a simpler method are welcome.
Well I use GlobalMapper and it opens them right up. Also supports a connected GPS device although I rarely use that feature. After opening in GlobalMapper you can export in almost any imaginable format.

Only problem is, GlobalMapper is expensive GIS software. But professional tools can make things much easier. Since I make my own complex maps, I would be lost without it. Unfortunately, a big company bought GlobalMapper several years ago and the price got even higher. But maybe you can find somebody selling an old version? I'm still running GlobalMapper 12 which has both 32 and 64 bit versions, but the geoPDF functions are only supported on the 32 bit version for some reason.

They have a free trial that won't export anything, don't know if it supports geoPDF however:

A quick Google search also found Avenza maps which runs on iOS and Android. They claim to offer support for PDF maps:
Originally Posted by werdnanostaw
Presumably, these are georeferenced in some way.

I do not see how the maps on UT's website are GeoPDFs...
Avenza looks nice IF you have actual GeoPDFs and you need to use pdf map files for annotation, etc. As the files I looked at, US 7.5x7.5-minute scale, are necessarily huge this would probably not be too good for touring.
Ha, I just looked and think you're right. They are just maps in PDF files, not GeoPDF's.

In that case, you would have to manually georeference them just like any other image. GlobalMapper does a nice job of that too, but probably overkill. You could use Photoshop to convert PDF files to JPG or TIF for OziExplorer. And IIRC, OziExplorer has a decent set of tools for georeferencing also.
I defer to your professional knowledge but is it possible that you downloaded other files and that the Vietnam files I have downloaded are GeoPDFs because in PDF Xchange Editor it says:

This PDF is a GeoPDF created by MAP2PDF. This viewer does not have the required plug-in installed to access the full geospatial functionality.

First two lines of the file say:

% TerraGo Technologies, Inc. pdf++ library
The Vietnam files are from USAF from ~1968. I wasn't going to use them for navigation - they're probably OK if you want to mount a bombing raid (sick joke). I was mainly interested in the topography which won't have changed since then.

We're travelling from Hanoi to HCMC by train which is the mode of transport least likely to need satnav because there's usually only one route to follow. We considered buses because they're faster and they go through the real world of streets and shops rather than through graffiti covered railway reserves, cuttings and tunnels but:

* Buses aren't as easy to book online and we needed to know in advance where we would be each night so we could book hotels.

* The bus stations are usually on the outskirts of town whereas the railway stations are usually in the downtown.

* The schedules are more predictable. The train that arrives at the scheduled time is usually the one going where you want to go. With buses in Asia where there are dozens of buses arriving all the time when you ask "Is that my bus?" you may be put on the wrong bus by a tout.

* Buses may leave from bus station or bus company's office or from hotel. Too hard.

* The signage is better. Once in Kyoto in Japan I got on squiggle1 squiggle2 squiggle3 bus but I should have got on only squiggle1 squiggle2 (possible squiggle3 was north, south, east or west - who knows). I ended up in the wrong place and I couldn't read the signs to work out how to get back and no one spoke English. Fortunately, around the corner from the suburban bus station there was a Metro station that had maps that showed me how to get back to the downtown.

If these files are georeferenced I could use them to see location on the very "pretty" maps but it's not the end of the world if I can't use them because I have a better solution for "pretty" navigation as compared to nRoute's very "unpretty" maps that I have downloaded from

OziExplorer can download OSM maps as you move around required area. The tiles are cached and can be used offline. It just needs patience to follow the railway line / coast at a suitable zoom level and then repeat each town / beach we will be staying at a "see all the streets" zoom level.

There was a program / web site (I don't recall which) that let you define an area on a map and and the required zoom level and it would download the Google tiles.

Does anyone know what it is please?

What program could the downloaded tiles be used in?

Is there an equivalent site for OSM?

Would the tiles be in a suitable format for Ozi and how would you persuade it to use them?

Some of these are probably rhetorical questions that I can / will answer myself with a bit of research but it would be good if someone could answer them.
Originally Posted by werdnanostaw
There was a program / web site (I don't recall which) that let you define an area on a map and and the required zoom level and it would download the Google tiles.

Does anyone know what it is please?
Maybe you are thinking of Mobile Atlas Creator?

But what you want to do is a violation of Google's terms of use that say you can only use their data with their own software and specifically forbids downloading for use in another program. Apparently they sent "cease and desist" orders to the authors of this and other programs several years ago. But there may still be some other programs that have remained under Google's radar.

I think Mobile Atlas Creator is great however, I have adopted it as a platform to distribute the maps I make myself because it allows users to export to a huge variety of other programs.

It sounds like you may have some real geoPDF's however. The couple files I looked at looked like plain PDF files. If you have real geoPDF's, that Avenza app would be worth a look.
One way of determining if a pdf file is a true GeoPDF file is to try to open it in Avenza. Even if a pdf image is as analogue as all get out (such as the CIA maps), I suppose in theory one could add the required geo-data as a "layer" to make it usable in Avenza or other such apps.

Even without geo-data, I could see that it would be worthwhile to have a few of these UT pdf and jpg files on one's mobile whilst in Vietnam. I am not sure the geo-data would be all that crucial. As you say, Andrew, you probably will not be confronted with too many navigational decisions particularly if you are relying on modes of transportation that tend to follow well-established routes. Somehow, we managed before GPS.

You can always save Google maps for off-line GPS mobile navigation, as I am sure you know.
Ken in Regina
Can't you download Google map segments for offline use in Google Earth? I'm not at a PC with Google Earth to check it at the moment.

I know that the default Maps app in Windows 10 will allow you to download Bing map segments for offline use.

Originally Posted by Ken in Regina
Can't you download Google map segments for offline use in Google Earth? ...
Can you get Google Earth on a phone? But why Google Earth as opposed to Google Maps? That is what the last line of my post was referring to. There are several ways of doing that. For instance, you can "Send to your Phone" from a Google Map open in Windows on a PC, you can "Share" a map, you can save to Google Drive, etc. You can then save the map on your mobile phone as a file that is usable off-line. Those files can be a bit biggish, but one needs them only between on-line bouts and deleted when no long relevant.
Ken in Regina
Apologies, I missed that.

The Android version of Google Maps has a specific, easy to use, function to download map segments for offline use. You can drag a box over the area you want to download and name it something meaningful. You can even do full function multipoint routing and some offline searching in the area you saved.

I tested it by planning a dream off-the-beaten-path motorcycle trip from here to Vancouver, BC, completely offline. I had to save three rectangular areas to get all of the map coverage for the trip planning. After that it just functioned as if I still had a connection.

Ken in Regina
In case you haven't discovered it, and for others who don't know, launch Android Google Maps, tap the hamburger menu (three horizontal bars) at the left side of the "Search here" box, and select "Offline Areas" in the menu list.

If you already have some offline areas you can manage them here. You need to update them periodically.

Maps will tell you how much space you need for each area so there should be no surprises about data or space utilizartion.

Ken in Regina
Maps is also smart enough to notice whether you are currently using a cellular data or WiFi connection. If it's a cellular data connection it asks if you want to use it or switch to WiFi.

...ken... About