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Author Topic: x + y Errors ok, heights to high  (Read 1856 times)

Bing66

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x + y Errors ok, heights to high
« on: September 16, 2015, 11:21:25 AM »
Hi
Not sure if anyone has any idea, 2 small projects, flown same day, 1 is 200m * 700m the other is 200m * 1.8Kms, all with accurate gcps, the difficult thing we had with this project was that it was a main road, and we had to keep away, so to get coverage we flew at 120m and only from 1 side of the road, no access on the other, the average errors are x = 2cm, y = 2cm, z = 1.2m, used gradual selection about 3 times, but doesnt seem to effect the height hardly at all, any ideas gratefully appreciated, ps we have carried our many commercial jobs, all successfully, this is the first time I have come across this
cheers

Bing66

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Re: x + y Errors ok, heights to high
« Reply #1 on: September 16, 2015, 05:29:11 PM »
ok, so my normal workflow was to use etrs89 as the reference system, the GCPs i was told were in OSGB36, so why when using osgb36 does the errors look wrong,, x + y about 8cm, z about 1.2 m! yet when using ETRS89, they are now sub cm in the x,y, and z, anyone shed any light on this