Has any one had problems with the two point localistion in fast survey VERSION 1.5 using Z-Maz RTK

Here is a summary of what we have been doing and then finding with our Thales Z-Max GPS.

Job A
Job Settings – Scale factor – Read GPS (approx 0.9996)

Localisation – 2points with 2 point rotate ON

Reads short, have to scale up approx 1.0004



Job B – Recent trip

Job Settings – scale factor – 1

Localisation – 2 points with 2 point rotate OFF – is the same localisation we have used ever since we have had machine, has been checked with EDM.

Read short unexplainably, had to scale work up approx 1.0004


Job C – Yesterday – distances measured against EDM over a kilometre

I went through a number of settings to test and try to get correct readings.



Job Settings - scale factor – 1

Localisation – 2 Points with 2 point rotate ON

Read short

Scale factor 1

No Localisation

Read short


Scale factor 1.0004

Localisation – 2 points with 2 point rotate ON

Read even shorter.



Then using coordinates from EDM, went about creating new 2 point localisation with scale factor set to 1 in Job Settings. 2 Point rotate turned OFF. When I stored both points, in the bottom left corner scale was still 1 and in H res the second point had an error of about 0.3. This I knew to be a problem. To try and jolt it into normality I went back to Job Settings and pressed read GPS to go to approx 0.9996. The localisation then looked OK with H res now 0 and scale approx 1.0003, however it still measured short. When I then changed the scale factor back to 1 in job settings, it read correct for the first time.



To me, it seems as though the localisation and the scale factor in job settings do not communicate to each other properly. When it is supposed to ignore one or the other, it won’t necessarily

I haven't experienced this problem, but I did notice your Fast Survey software is out of date. Fast Survey 2.0.5 is now available on the FTP site. If you upgrade you will need an change code, so please do not upgrade until you can allow a response from Magellan with the code.

Here is the link to upgrade, I am not sure if this would solve your problem, but it is a good place to start.

FAST Survey

This may or may not be an issue with what you are doing, but I'll toss it out here anyway.

When you set the base with an autonomous position (by "read GPS") make sure the base has been running long enough--10-15 minutes---to actually average a pretty good ellipsoid height, and have a reasonably good idea of the actual orthometric height (elevation) of the local position of your base from say a quad map to compare with. I'm talking better than 50' in elevation for the comparison.
THEN if your project you are attempting to localize upon has for instance assumed elevations that are quite a bit different from the actual "reasonable" orthometric height, then yes, the scale factors can screw up. In other words, if you are working at elevation 800' MSL and trying to localize to a coordinate file with assumed elevations of 100, that could be a lot of your problems.

However! Since you set the base by "read base" and are using an autonomous XY and Z, document document document and add a tad of metadata to your projects so others don't take them as "the gospel"!

Dangerous Dave

Modified By Dave Huff on 2/25/2008 at 2:26 AM