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Jackaroo
12th November 2005, 07:43 AM
Hi Guys

I notice we have a State Map OziExplorer Calibration File for all states except Australia

Does anyone have a State Map OziExplorer Calibration File for Western Australia. I have tried to Import and calibrate the map myself but it never seems to work out right

helterskelter400
12th November 2005, 09:06 AM
is this what you are after. its not 100% accurate but its better than nothing.

Jackaroo
12th November 2005, 12:42 PM
is this what you are after. its not 100% accurate but its better than nothing.

Yes, thats what I was after. It seems that your *.map file is more accurate than the one I tried to calibrate. Always seems to be a little bit out.

Thanks

arthurking83
12th November 2005, 01:13 PM
Howdy guys!

Helter, how come you used "lambert conical" for the projection?

I made up a calibration file too, but used the same projection as the the files KGB posted.....Lat/Lon!

I don't know very much about projections, and datums, etc.....
but I'm curious as to why you chose that?

cheers

helterskelter400
12th November 2005, 01:26 PM
hey man, i didnt make that file, i got it via a link on this forum somewhere a while ago. someone found the full set of map files for those hema state maps and posted a link & i folowed it; as you do.

arthurking83
12th November 2005, 01:31 PM
..... and posted a link & i folowed it; as you do. :D :D

As we all do! Half my life has been whittles away following links ;)

Try my calibration file.........it's done in lat/lon.
I have no reference points to check.


cheers.

Jackaroo
12th November 2005, 02:06 PM
:D :D

As we all do! Half my life has been whittles away following links ;)

Try my calibration file.........it's done in lat/lon.
I have no reference points to check.


cheers.

Thanks arthurking83
Have tried you file, just loaded it in Ozi then pointed to one of the Lat/Lon lines on the map

Ozi shows that the calibration is out by
- 3 mins S
-33 mins E

Maybe I am doing somthing wrong, but the first file seem to be a lot closer than yours :(

helterskelter400
12th November 2005, 02:17 PM
i just had a test of the map file i found and posted and the one arthur posted. tested them against corresponding points on raster 250k 2003 release.

arthur.map
mount barker townsite in south of wa
the wa map was out by approx 27km on a bearing of 70 degrees
Roebuck Plains Roadhouse in north of WA
the wa map was out by approx 18km on a bearing of 330 degrees

i found.map
mount barker townsite in south of wa
the wa map was out by approx 4.7km on a bearing of 52 degrees
Roebuck Plains Roadhouse in north of WA
the wa map was out by approx 9km on a bearing of 7 degrees

whoever made the map files that were linked ages ago, knew their stuff.

arthurking83
12th November 2005, 02:29 PM
OK I haven't really tested the calibrations (I have a list of WA waypoints that I'll have to manually enter [from a **** Smith 'Australian GPS Location Guide, ed1 !! :D ])

I did what Jackaroo did!........most terribly embarrassing :o
So I uploaded a new file (@ 5:25PM)
This time I used the 'polynomial" function.......I want to see if that helps?

(I can't figure out the "Originating Meridian" for the Lambert conformal :confused:

hope that is better

Jackaroo
12th November 2005, 02:58 PM
Ok

Had another play, learnt a few things about calibration from previous posts. Did not even notice the lat/long lines were curved :o

This file is a combination of 5 calibration files to get a file with 30 calibration points
Also used the polynomial option and UTM

Jackaroo
12th November 2005, 03:06 PM
hmmmm

kgb has been back and posted a map file for the WA State file. Will give me somwthing to compare with

arthurking83
12th November 2005, 03:09 PM
.....
This file is a combination of 5 calibration files to get a file with 30 calibration points
Also used the polynomial option and UTM


How come the UTM?
I think you should have used the Lat/Lon, because UTM describes a square grid on a map, ie. the projection will be wrong (a bit!) For such a large map (like a State or country) it won't matter too much.

But I'm sure it will be "more accurate" if it was lat/lon :confused:

cheers.

Jackaroo
12th November 2005, 04:47 PM
How come the UTM?
I think you should have used the Lat/Lon, because UTM describes a square grid on a map, ie. the projection will be wrong (a bit!) For such a large map (like a State or country) it won't matter too much.

But I'm sure it will be "more accurate" if it was lat/lon :confused:

cheers.

Was something i read in the OziExporer help file



When dealing with maps with curved Lat/Lon lines and you are not sure of the projection it is advisable to try calibrating using the Transverse Mercator projection as this is the most common for general purpose topographic maps.


Don't know if it is correct or not, still have lots to learn :)

arthurking83
12th November 2005, 05:32 PM
ROLF! :D

I should learn to.....RTFM!!


I usually just fumble around, but reading the manual is always a big help!!

Also I would have assumed that using the 'polynomial' option would be the "best" case as it's supposed to work out some super heavy duty maths equation stuff to translate an elliptic projection into a square picture?? :confused:

but like I said I've yet to read the manual, so I should stop guessing!!

Edit: Oh yeah! there is a chioce of Transverse Mercator and UTM!!
ie. they are two different projection!