Tag Archives: MacGPS Pro

Bushwalking Navigation | How to make a customised, calibrated map from an .ecw map file.

Do you have a Mac computer? Want to know how to use a ecw map file to produce a customised, calibrated, topographic map? Don’t know which software to use? Don’t want to use a Windows emulator? Not sure which map datum to use?

UPDATE (Tuesday 3 July): advice on calibrating TOPOMaps version 2 ecw files  modified

The following discussion relates exclusively to two highly regarded Mac applications that I, and millions of other Mac users, have been using for what seems like a lifetime. Both are fully supported with user forums, have a prompt response to enquiries, are low cost for what you are getting, and are actively being updated by developers who have a love for Macs. These applications are

It is of course possible to use OziExplorer on a Windows computer or emulate a Windows machine on your Mac, but these are a poor substitute for powerful, user friendly software, running natively on a Mac.

I assume that you are using the latest version of Graphic Converter (GC) (there is a trial period so you can fully test it before purchasing) and have it running in 32 bit mode. You can do this by control clicking on the GC file icon, selecting the Get Info box and then checking the  “Open in 32 bit mode” check box if this choice is available [ see diagram] NB  ecw files won’t open in 64 bit mode and you will get an error message if you try to do so.

MacGPS Pro doesn’t have a demo version, but it does have a 30 day money-back guarantee.

iOS Applications

MacGPS Pro also has an iPhone/iPad/iTouch version iHikeGPS which is  suitable for New Zealanders and North Americans, due to the availability of free maps. Australians miss out as our maps have to be purchased.

Bit Map (Australian design) allows uploading and viewing of custom maps made using the technique outlined below, using an iPad or iPhone, which is something that few other apps can do. While its plotting features are not as complete as MacGPS Pro, it does allow the plotting of waypoints and routes,  or uploading from an OS X mapping application such as MacGPS Pro via iTunes. Like MacGPS Pro it allows live viewing of your current position using the built in GPS.

Disclaimer: I have no relationship with the  developers of the software discussed above.

For my review of Bit Map click this link.

Steps

IMPORTANT: If you have a small (a few map tiles only) .ecw file and the accompanying .map geo-referencing file is in the same  folder, then MacGPS Pro will open and calibrate the ecw file, as soon as your drop it on the MacGPS icon, without any further action on your part. If you don’t have the corresponding .map file then you will need to calibrate the newly imported ecw file as in Step 7.

    1.    Drag  the  ecw file from your CD to the GC icon, and dialogue box below will pop up. Select a slightly bigger area than you want by dragging the square corners of the large box [see diagram below] and then position the box by dragging from the middle of the box. Select Downsample.”None”, then click OK. HINT: It doesn’t need to be accurate at this stage. Just make sure the area of interest is inside the selected area.

  2.    Select the part of the image you want by using the selection tool (the dashed square, second line on the right) [see diagram] from the toolbox (bring to forefront by clicking command-K)  and save as (file/save as) a pict file, which is the native MacGPS Pro format. Make sure you have checked the radio button Save Selection Only.[see diagram below]  [Steps: name file, select file format ie PICT, check save selection only]

 3.    Open Mac GPS Pro, set the units (file/unit choices) to the appropriate datum,
which should correspond to the map datum of the paper maps you have or will be purchasing.

If you intend printing labelled maps directly from MacGPSPro as pdfs, then I would suggest you set to GDA94, as this is most likely to be compatible with the maps of others in your group.

 eg GDA94, UTM, kilometres, metres magnetic, click OK. [see diagram below]

    4.    Drag the cropped pict  file from your Finder onto the MacGPS Pro icon.
    5.    A dialogue box will open and ask you to “Set the map’s Datum  and Projection type”  [see diagram below] Select GDA94 for most discs recent mapping discs and Transverse Mercator. Click OK

    6.    It will then pop up a “Standard Coordinates for the Map” dialogue box. Enter the grid zone (see image)

and check the ‘Store calibration in PICT file” box, then OK [see diagram below]

    7.    You will then have a “Click known Points to Calibrate Map ” dialogue box pop up. Check the map datum is set to the same as your hard copy maps before proceeding. [see diagram below]

Complete this for any four easily recognized features (eg trig point, windmill)  located near the four corners of the map, using a hard copy of the map to provide the 7 digit eastings [eg 0262600] and northings [eg 6553800]. Click DONE.

HINT: Make sure you have zoomed in as far as you can, without the map becoming too pixelated, using the zoom icon top right, to increase your accuracy.
 
VERY IMPORTANT: If you are using an ecw file from a TOPOMaps version 2 disc (South Australian), then be aware that the grid lines on the ecw file are those of the AGD84 datum, as the file has been scanned from pre-94 maps. If however, you open these maps in OziExplorer you will find that the associated .map file (found on the disc) has calibrated the maps as GDA94 hence the disc markings.

The Instructions file on the disc ( who reads the instructions?!) say

The map image displayed (in OziExplorer) has been recalibrated to the Geocentric Datum of Australia 1994 (GDA94). The Easting and Northing readouts for any point at the cursor position will in GDA (94) coordinates.

Please Note:
The map images were scanned from AMG 84 based maps. Therefore, if the cursor is placed at the intersection of two grid lines, the coordinate readout will not correspond to the values of those grid lines. Future map editions will display a grid pattern based on the GDA94 datum and therefore the readout will then correspond to the grid values. See also p25

The warning above is very important, if you normally use grid line intersections as your calibration points, as this will result in inaccurate calibration, with the whole map displaced 100-200m. If you use recognized topographic features this problem doesn’t exist.

HINT: To speed up the process in case you need to start over again, keep a record by printing a copy of the map and annotating it with the four corner grid references which you previously entered. If MacGPS Pro won’t let you click the DONE button it is probably because you made a mistake entering the GR and will need to start again, or perhaps you have failed to select a point on the map, to register the grid reference.

The Ultimate Goal

Remember that the goal of calibrating a map, plotting waypoints and joining them to form a route using MacGPS Pro is so that you can transfer them to your GPS and use your GPS to find your location relative to these waypoints, on either a purchased map or one printed using the software. For this reason, the map datum set in your GPS MUST match the paper map you are carrying.

My next few posts will explain how to export your data from MacGPS Pro to your GPS, overlay the calibrated map you have produced on Google Earth to help you visualize the terrain and get the UTM coordinates from Google Earth by overlaying with UTM grid.

Visit some of my other related navigation posts

  Creative Commons LicenseThis article by Bush Walker is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 3.0 Unported License.

Bushwalking Navigation | Documenting Your Route Plan

How do you document a route plan? How can you use Google Earth to check the route and save pics of critical navigational decision points? How do you use mapping software to plot and export the waypoints to your GPS, print the route and elevation graph? How can you annotate your map pdfs? How do you protect your maps from the weather?

This post is part 2 of  Bushwalking Navigation | A Route Plan Workflow

Getting the “big picture”

The first step in planning any trip is to read guide books, talk to other bushwalkers and search  bushwalking forums, websites and blogs to discover which routes are popular. 

Once you have decided on your intended route you will need to check water availability, weather conditions, locate existing tracks, property boundaries and permitted camping spots.  Don’t forget to check photographic websites such as Flickr, which give a good idea of popular sites and the scenery to be expected.

Next study the terrain to work out your likely speed, keeping in mind height gains and losses, the density of vegetation, the amount and difficulty of any off-track walking, and the presence of waterfalls in creek lines, which may need to be bypassed.  Once you know these you will be able decide how far apart your camping spots can be and determine each day’s starting and finishing times.

I have discussed many of these navigation techniques and route plan design in previous posts (21) and won’t go further into detail now.

Finding a Map

You should never rely solely upon a GPS for critical navigational decisions and for this reason bushwalkers should always carry topographic maps covering the route, and the surrounding countryside just in case you get off track. These can be purchased from a local map or outdoors shop, and are usually available at 1:50,000 scale but sometimes at 1:25,000, which provide more detail, for popular areas.

If you are walking the Heysen Trail in South Australia, there are two excellent guide books (Northern and Southern), with log books readily available available which include maps that are adequate for most walkers. The CFS also publishes (Mapland) excellent map books, and these too are available from map and outdoor shops. Many downloadable walking brochures for our parks are available from the Department of Environment’s Parks SA website.

With digital maps readily available, many people are using mapping software to select just the relevant parts of maps and to enlarge these beyond the 1:50K scale than is usually available in printed maps, making it easier to see the contour and creek lines. If you are lucky enough to live in NZ, you can download 1:50,000 maps free of charge and even Australia has 1:250,000 maps for free download from Geoscience which are useful for getting the big picture and planning access roads.

Using Mapping Software

My apologies to Windows users for the following Mac centric discussion. 

As a MacBook Pro user I have used MacGPS Pro mapping software for many years to import my scanned maps, plot my routes and export the waypoints to my GPS. A print out of the waypoints file is an essential record of each waypoint’s  name, grid reference, comments, and elevation

One big advantage of mapping software is that it is possible to enlarge the map on screen to locate the exact position of known waypoints  or to determine the grid reference to 7 figure accuracy of any point you can see. Once you have decided on your waypoints you can rapidly link these to form a route, calculating distances and bearings automatically by dragging from point to point, and plotting a route elevation graph by selecting the route single click. The elevation graph is useful for estimating time to be taken.

From MacGPS Pro

The disadvantage of using a Macintosh is that without a Windows emulator, such as Bootcamp, and an installed version of Windows, OziExplorer software doesn’t work.

For older Macs (not using intel cpu) use Virtual PC or for new OS X Macs with the Intel CPU use either Bootcamp or emulation software called VirtualBox or ParallelsVirtualBox (Sun Microsystems Inc.) is free for personal use. It works in OS X on Intel Macs. (OziExplorer – Running OziExplorer on a MAC or Linux Computer )

There is a way to overcome this and that is to import the maps from the disc in .ecw format into a graphics program such as Graphic Converter, select the relevant part and then save as a PICT or TIFF file.  Some of the .ecw image files are small enough to import directly into a mapping program such as MacGPS Pro.

Often the .ecw image file will be accompanied by a matching .map calibration file and providing you keep it in the same folder as the ecw file, you can then import into MacGPS Pro and automatically calibrate the map. You could of course still do it the old way which was to scan and process a hard copy of the map.

Assuming there is no matching .map file available, calibrating a digital map using MacGPS Pro requires that you first rotate the map (using GraphicConverter) so the northing gridlines are horizontal and then enter the full 7 figure grid references of four widely spread points, usually near the corners of your map.

Top Left:  Easting 0263000 Northing 6540000, Grid Zone 54J, AGD94

From MacGPS Pro

You must also enter the UTM grid zone and know the projection and map datum eg I am using a portion of the Oraparinna map for a forthcoming trip

From MacGPS Pro

NB UTM Grid Zones is SA are either 52 (far west), 53 (west) or 54 (central and east)

Annotating your pdfs

Annotated portion of Oraparinna map

There are several programs (I use Skim) that allow you to annotate a pdf. This is particularly useful as it allows you to add grid references to the margins of your map (NB MacGPS Pro has a menu item “View/Gridlines” which does this automatically for you) and add notes about the route. Most programs allow you to add arrows showing routes and highlights. Once you have done this, you can export as a pdf and if you have the full version of Acrobat take advantage of its ability to reduce the file size significantly, to as much as a tenth.

Using Google Earth to Plan a Route

Google Earth can be used to visualize the route, finding 4WD tracks, checking whether creek lines are heavily vegetated and to see if ridges would be easier going. Cattle, goat and sheep tracks converging on a creek line probably indicates a waterhole, spring or a shallow crossing. Rainwater tanks, galvanised iron shelters, windmills and bores can sometimes be seen in Google Earth, even if they are not marked on the map.

Flinders Ranges: Google Earth screen capture

Simply import your .kml file showing your waypoints and then zoom in and tilt to see your route in 3D. Use a screen capture program, such as  Snapz Pro X, to capture pics of significant parts of the route, with your waypoints shown. Save these to your iPhone, camera or print, for later reference while on the walk.

NB I can never get my GPS waypoints to exactly match those in Google Earth, as I assume it uses a different map datum

Protecting your maps

One of the advantages of printing your maps from pdfs is that you can print them in A4 format which means they can either be laminated back-to-back or placed in a map case without the need for folding.

Other relevant posts

The Bushwalking Navigation series

Other Resources

Geoscience
Department of Environment’s Parks SA website
Bushwalk Australia Forum
Friends of the Heysen Trail

  Creative Commons LicenseThis article by Bush Walker is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 3.0 Unported License.

Bushwalking Navigation | Using the Free Geoscience Australia Maps

What does the Geoscience Australia website offer to bushwalkers? Want some free topographic maps covering the whole of Australia for planning purposes?  Want to view these maps using your desktop mapping software? Want to load them into your iPhone?

MapConnect

“Delivering online mapping tools and information, this interactive service allows you to download Australian maps and data for FREE. MapConnect is useful to professionals or students working with spatial data. The general public is welcome to use this resource, but should note that some aspects of MapConnect are specialised. You can view selected data on a map then download it in various formats.

MapConnect is a FREE service, data can be downloaded using the interactive map selection process.

MapConnect can provide mapping data in four ways:

  •     250K – 1:250 000 scale topographic map data in .ecw format
  •     GlobalMap – 1:1 million scale topographic map data
  •     Geology – 1:1 million and 1:2.5 million scale geological map data
  •     geoMAP – Create a quality PDF map in either of 2 formats ( satellite or topo)
Gammon Ranges, SA, 250K Landsat (MapConnect Geoscience Australia)
Gammon  Ranges SA  Standard  (MapConnect Geoscience Australia)

 Loading MapConnect Maps into your desktop software.


The maps, in two formats .ecw amd .kml are downloaded in a zip file. ecw files are geo-referenced and can be loaded directly into mapping software such as MacGPS Pro (for Mac enthusiasts) and a variety of software for PC users. This will allow you to plot waypoints, routes and then upload the points/ routes directly to your GPS.

Suitability of 250K Maps for Bushwalking.

250 K maps really only allow you to get the big picture, select likely bushwalking areas, plan your approach and navigate by road. On-the-ground requires 25K or 50K topographic maps which will need to be bought as hard copies or in digital form on disc. Check the above 250K maps as examples of the resolution you can obtain.

Geoscience Australia Maps for your iPhone

This will require converting the highly compressed  .ecw format maps ( typically 5 Mb) to .png (typically 31Mb) or .jpg (4Mb at 50%). For better quality, save as .png, which is a lossless format like tiff. To do this read my review of  BitMap

Further Reading

    Related Bushwalking Navigation Posts
    Related iPhone Posts for Bushwalkers
    Related Bushwalk Planning Posts

      Creative Commons License This article by Bush Walker is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 3.0 Unported License.