250K Raster maps now online

Hello - Yes I was wondering not only how people who have purchased the maps recently feel, in addition to those who sell it. It is of course good for everyone in the long term that they are now available "free". It has been anticipated for several years as it is GA's policy to make data freely available when they can. The transition from user pays to free will always cause problems. In GA's defence the digital maps were actually pretty cheap (per map) anyway and it also includes the viewing software and gazetteer. It would also be a bit of a pain to download the entire set. Good for updating the maps you already have though when new editions become available...previously not possible (through GA). I doubt if the Mosaic will be made available online in the near future and that is actually a better option for most.
Cheers
Greg

They all appear to be there,
I've just downloaded the Perth Special

I go into the following URL
https://www.ga.gov.au/products/servlet/controller?event=DEFINE_PRODUCTS

there is then a button called "define an area of interest" that will bring up a map of Aust where you can select from.

Calibration within Ozi seems fine to me

Hello
Calibration Data for ecw files is generally included within file itself as a "header" (ie not a separate file) ..the maps in question have this info. You can import calibrated ecw files into Oziexplorer easily using the FILE - IMPORT MAPS - ECW MAPS function.
Cheers
Greg

It's well known that the cailbration data included in the Auslig/Natmap 250k:1 maps is nowhere near good enough for navigation use in OziExplorer or other mapping programs.

You can't use the .map calibration files for the Natmap 2005 standard edition from the GPSOz or OziExplorer websites as these are for UTM projection and the maps available for download are the Geographic Lat/Long projection. They cannot be used for accurate distance measurement as in distance terms the pixels are not all the same size.

So someone will have to manually correct the calibration of all of the files...

Peter

I have downloaded, unzipped and imported a number of the maps into OziExplorer. The calibration seems fine. With grid lines turned on the cut exactly through the tick marks on the map.
Bruce

Thanks Greg,

I imported one and it did had the calibration data but only 2 points
for the whole map...
Tried it on the day trip today and the location on the map
was a few km off compared to where I really was....

So I guess as Peter mentioned can't use them for navigation but
the maps might be useful for planning your routes instead/in addition to of using paper maps.

Can I sugest that you check the datum set on your GPS. There is no way the calibration is a few kms out. I cannot check as I am in the UK at the moment, but when you turn on grid lines they look exactly correct.

Don't worry about "only 2 points" This is normally the case with this typs of imbedded calibration.

Just checked with some tracks I recorded in Oz - tracks are right down the middle of the road, so the calibration must be OK.

By jingoes - there is NOTHING wrong with these maps (well the ones I have downloaded) - they work perfectly in OziExplorer and the included ecw header calibration is spot on (as one would expect). Anyone having problems should, as a suggestion, first revisit their method of import into OziExplorer, double check their GPS/OziExplorer configuration settings (eg use a map they know is right) and then ask someone to download the same maps and check it also. As correctly pointed out two calibration points are all that is needed for perfectly geo-rectified images such as these (meters per pixel up and across map are the same). You only need more than 2 if the image is not "square" ie projected and distance per pixel across the map is different to that down the map (not the case here)

...pjchris posted this followup

"It's well known that the calibration data included in the Auslig/Natmap 250k:1 maps is nowhere near good enough for navigation use in OziExplorer or other mapping programs."

Not correct - from my limited knowledge on the subject this was an issue with the first release of the natmap mosaic a year or two ago ..a later release of OziExplorer fixed the problem and as a consequence the issue no longer exists ....obviously a less well known fact. Another issue with respect to ecw file calibration existed with individual mapsheets prior to them being geo-rectified and hence the warning you get when you import ecw natmaps (which applies to series 2 maps ONLY)..no longer applies to newer editions. Download and have fun..its ok
Cheers
Greg

Meters/pixel up and across the page are NOT the same with these images. They are Lat/Long projection so degrees and minutes per pixel is identical all over the map but metres are not.
That's why the maps look a little squashed vertically (or stretched horizontally).

I have checked the calibration of two different maps from the Natmap 2003 Cd's, one in Qld and one in Vic and the calibration in the CD .ecw is exactly the same as the calibration in the .map files downloaded from the Ozi explorer website. So calibration should not generally be an issue

However I believe that the calibration on SOME maps is out. I own all of the Victorian 1:100,000 maps and one of those has the calibration info from a map 500km away, and one of the others is actually triangular when imported in to Ozi. It's not, of course, it's square.

The main reason for the downloadable .map files for the CD's is that while the calibration is mostly OK the corner markers are not. They include the entire image, Legend, border and all. This won't matter withe the ecw files dowloaded from GeoScience as these files contain just the map image. No borders, legends etc.

I have a job set up to download all of the available files from GeoScience at work tomorrow and I will load up a couple from SA (I have a lot of tracks from around Mt Gambier, and will check the tracks I recorded on a trip to Brisbane to see how well they are calibrated.

I will let you all know how I go.

Peter

Woops stand corrected - yes not metres but degrees...anyway bottom line - images work fine in OziExplorer (as good as a 250K scale map could be) ..obviously some issues arising with respect to some maps - if you find an error let GA know and they will fix it I am sure.
Cheers
Greg

Hey Pajman, I bought it also and am happy that I forked out the cash and got the mosaic. I know you can stitch the individual maps, but i would rather be doing trips than sitting home stitching maps together.

Hello - I am lead to believe the map files you speak of do not work with the downloadble maps as theses map images have been cropped to reduce file size ie calibration points will be in wrong spot as image shape and dimensions have been altered. I dont know if this is actually true as I havent bothered to download one as yet. Its easy to import calibration anyway so no big deal.

With respect to change file image path - not sure what you issue is as if you can change one you should be able to change all. If the file attributes are in fact read only and this is causing the issue ..just change file attributes for the map files (select all files at once then right click and select Properties and unselect Read Only). If you keep the map calibration files in the same directory as the images it doesnt actually matter what the image path is set to anyway as OziExplorer looks in image file directory first what ever you have image path set to.

Cheers
Greg

Hello - if you have OziExplorer (free trial/demo version at
OziExplorer web site
) you can open them ..if however you dont wish to go down that path you can get erviewer
at
erviewer

Cheers
Greg

Thanks Greg.

Some people have been busy!
With respect to my earlier comment on compatability with OziExplorer - I looked up history of changes and found this
Release Version 3.95.3c (September-2003)
Changes
•Geoscience Australia has released the new 250K Mosaic map of Australia. This map is in a geographic projection (latitude/Longitude) so is not a constant horizontal scale when when moving north/south. OziExplorer has been modified to recognize the varying scale and make adjustments when drawing objects on the map. Example - proximity zones and range rings will plot as ellipses so the distances are correct.

Does get a bit confusing all these datums/projections/metres/degrees - no wonder Im crackers
Cheers
Greg

"so I'll probably use Global Mapper to change them to UTM projection and square (meter) pixels. "

Hasnt this been done already with the individual map tiles avialable on CD/DVD ? Being self emplyed I figure the amount of time it would take to do (if you were doing all of them) at my normal charge out rate would equate to a lot more than the cost of purchasing the CD/DVD (a tax deduction as well) ie my time could be better spent eg writing posts on forums!
Cheers
Greg

Yes Greg, the Cd's/DVD's are in UTM format so if you wanted that format and didn't have the time or ability to download them that would be the way to go.

I actually own the Natmap 2005 Raster premium on DVD and the thing that interests me about the downloads is that there are maps available for download that are newer than those on the CD's or DVD's and there is no way to update the Cd/DVD maps until the release of NatMAP 2006 when you just buy the disks again.

Peter

Peter - yes that is indeed one major advantage of the downloads - getting the latest and greatest - they seem to have updated quiet a few recently. I have never bothered to look at Global Mapper - (I use Arcview) - is there a "demo" version that allows re-projection of images(or whatever you call it) or do you need to fork out some $ (as with ArcView..which I think? does it to, but never tried).
Cheers
Greg

Hi Greg,

Yes there is a demo of Global Mapper at
http://www.globalmapper.com

Quote:
You can freely use the latest version of Global Mapper that you downloaded and installed. However, without a valid username and registration key, several significant functions will be unavailable. In particular, if you do not obtain a valid registration key for your copy of Global Mapper you will be subject to the following limitations:

* You will be unable to export data to any format.
* You will be limited to loading a maximum of 4 data files at a time. With the full version, you can load any number of data files simultaneously.
* You will be unable to view loaded elevation data in 3D.
* You will be unable to load workspaces.
* You will be unable to do line of sight calculations using loaded elevation data.
* You will be unable to perform view shed analysis using loaded elevation data.
* You will be unable to perform cut-and-fill volume calculations using loaded elevation data.
* You will be unable to work with map catalogs.
* You will be unable to save rectified imagery to fully rectified files.
* You will not be able to print to a specific scale (i.e. 1:1000).
* You will have to endure a nagging registration dialog everytime that you run the program.
* You will not be eligible for free email support.

Cheers,
Peter

Hi Bruce,

I sent them an email reporting this at lunch time and Geoff from GeoScience replied that they would fix the problem overnight so the files should be fixed tomorrow.

Peter

SH5414 now will download sucessfully.

Peter

Peter,

Thanks for the info. I now have the complete set.
Bruce