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Messages - Isaac H. E.

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31
Bug Reports / Re: geoid sign seems to be wrongly applied
« on: September 11, 2017, 11:38:17 AM »
Hello Alexey,

Please accept my most sincere apologise for this forum post, I'm flying a DJI Mavic Pro and indeed it outputs what me may call "GPS altitude" but today I discovered that the height of the take off point I was using (in clear view of the sky with virtually no multipath) has "errors" of more ( :-[) than 100m between two flights separated 4 days, that is obviously unacceptable for photogrammetric processing.

Sumarizing I assumed that the EXIF reproted height was elliposidal when in fact, due to errors, it is impossible to tell if it is ellipsoidal, ortometric or some other reference level.

This case can be closed, many thanks for your help.

Isaac

32
Bug Reports / geoid sign seems to be wrongly applied
« on: September 09, 2017, 12:07:47 PM »
Dear sir / madam,

I started a PS project where I imported 800 JPGs all with WGS84 coordinates and ellipsoidal eights in the EXIF

I have downloaded the EGM2008 1' geoid model (EPSG::1027) from http://download.agisoft.com/geoids/egm2008-1.tif then I placed the file within PS geoids folder and then I created a new "Coordinate System" as follows:
Projected Coordinate System: WGS 84 / UTM zone 31N (EPSG::32631)
Projection Method: Transverse Mercator
    Latitude of natural origin: 0
    Longitude of natural origin: 3
    Scale factor at natural origin: 0.9996
    False Easting: 500000
    False Northing: 0
Geographic Coordinate System: WGS 84 (EPSG::4326)
Geodetic Datum: World Geodetic System 1984 (EPSG::6326)
Ellipsoid: WGS 84 (EPSG::7030)
Prime Meridian: Greenwich (EPSG::8901)
Linear Units: metre (EPSG::9001)
Vertical Datum: EGM2008 geoid (EPSG::1027)


When I output a DEM from PS and I compare that PS DEM heights against a DEM published by the official local cartographic institution the heights of the PS DEM are wrong by 2 times the geoid undulation in other words it seems that the geoid is being applied in the wrong direction.

Thanks

Isaac

33
Feature Requests / WGS84 to ETRS89 datum transformation
« on: September 08, 2017, 06:58:38 PM »
Hi,

I believe that as of now PS is only able to apply 7 parameters datum transformation however to consistently transform from WGS84 to ETRS89 it is necessary to input time based parameters (14 parameter transformation).

If I´m correct now PS assumes the datum transformation between WGS84 and ETRS89 as X:0 Y:0 Z:0 rX:0 rY:0 rZ:0 ppm:0 which is acceptable if metric accuracy is sufficient but is not acceptable for survey work (sub centimetre).

Thanks for your time and effort.

Isaac

34
General / PhotoScan OpenCL GPGPU of choice
« on: June 21, 2014, 09:38:08 PM »
I have seen http://us.hardware.info/reviews/5231/9/nvidia-geforce-gtx-titan-black-4-way-sli-review-gpgpu-benchmarks---double-precision-fp and to be honest I have no clue on how to proceed...

Thanks for taking the time

Isaac

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