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a) updated 21st April April 2012 GOOGLE EARTH: Google Satellite Map Downloader

• For areas where coverage is not available from Nearmap using Google Satellite Map Downloader gets a good quality image. By default the programme produces a 16bit bmp file. This is not supported by OCAD so load it in a graphics programme and save as a standard 24bit Windows bitmap. Alternatively you can save the file as a jpg or tiff file.  . If you would like to learn more about world coordinates files try this link provided by Peter Hoban: http://www.cryer.co.uk/file-types/t/tfw.htm  This format also applies to jgw and bmpw files.
• The world maps generated by this programme are not compatible with OCAD. The good news is that Peter Hoban (The cool climate in Tasmania must generate lots of good ideas!) has developed a spreadsheet, based on the wisdom of many others he tells me, that will convert the associated world file into a file that is compatible with OCAD 10 & above. What is involved is described below by Peter. I have tested the process with two already accurately calibrated maps & found the spreadsheet conversion to be very accurate within the limitations of Google Earth itself.

"I have learned that Google Earth uses decimal degrees to locate their images, so the Google Satellite Maps Downloader will use these also.  Experiment showed that this too is the unit of the scale factor.  Conversion of those coordinates to say a UTM grid based on WGS84 or anything more recent is not easy and may be beyond them.  (The more recent coordinate systems differ from WGS84 by only a few centimetres.  WGS84 is also the default UTM coordinate system for every GPS I have ever used.)  The coordinates provided are those for the top left corner of the image. When you make a map in OCAD you are able to create a world coordinate system and this expects a UTM system like WGS84. In order to get the downloaded Google images to open correctly located and scaled in OCAD10 it is necessary to convert the *.jgw file to  appropriate UTM units.  I have managed to make (largely copied from the work of others) a spreadsheet to do this. For a downloaded Google image open the *.jgw file in a text editor and save a fallback copy with a different file name or extension.  Open the original file again and copy the contents.  Open the converter  and paste the contents of the .jgw file into the input (left) box.  The right box will then have your converted data in WGS84 UTM coordinates.  Note that the scale factors should now be about equal (within 1%).  Copy the converted data back to the originally named .jgw file.
The image should then open correctly located and scaled in your OCAD10 map.
The converter is protected except for those cells into which you are required to paste data.  The protection is only for convenience - the password is blank (no password)".

The Converter zip file contains both an open office & excel version of the spreadsheet: 

a) NEARMAP High quality photography from all over the World. Thanks to Paul Dowling for the helpful information he provided below  on making the best use of this photography and how to get it into OCAD......update 28th April 2012..as you will see from Nearmap website they seem to have now gone totally commercial so be prepared to pay. I left the article below in place as it still works with some other map sources. If you want to use Nearmap photograph you will need to get a licence & a copy of Hypertiles. Those who have an existing licence seem to be able to access nearmap at least for the present. With the default jpg file & associated world file it imports without drama in to OCAD 10 & 11. Manual adjustment is necessary with OCAD 9.

First: Download Mobile Atlas Creator: (only helpful with OCAD 9 as direct import is possible with 10 & 11 using Hypertiles)

http://sourceforge.net/projects/trekbuddyatlasc/

 As of v1.7, MAC natively supports Nearmap’s photomaps, along with just about every other online mapping source on the planet. :)

 To use:

·         Start MAC

·         Select Nearmap Australia from the Map Source dropdown.

·         Find the area you want (right-click/drag to move the map, mouse wheel to zoom in)

·         Turn the Grid on (dropdown, top left corner) and set to level 19 or 20 – this is just to get an idea of how many tiles you’ll be getting.

·         Left-click/drag the area you want to download.

·         Select the zoom level(s) you want from the check boxes in the top left. Note the tile count – if you grab too many at a time, Nearmap’s servers will sometimes boot you off for a while. The limit varies with server load, so if you’re trying to do a big download then do it late at night.

·         Once you’ve selected the area and zoom level, enter something meaningful in the Name: box on the left and click Add Selection.

·         Right-click the “Unnamed atlas” in the Content box and click Rename, call it something meaningful. This is the directory it’ll store the image in.

·         Change the Atlas format to OziExplorer so it’ll generate a PNG file.

·         Click Create atlas and let it do its thing.

·         When it’s done, click Open Atlas Folder and you’ll see a list of directories (this is where renaming the “Unnamed Atlas” is handy!) find yours and a couple of directories down you’ll find a (sometimes very large) PNG file. You’ll have to convert it to JPG, BMP or TIF for OCAD to read it.

 There appears to be no limit on how big an image you can create, as long as Nearmap’s server doesn’t throttle you – I’ve generated ~800mb PNG files using this program.

by Paul Dowling

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