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mao90210
75 post(s)
#27-Sep-18 03:46

Hi everyone, i need some help of my custom projection.

I have a cadastral boundary drawing and i need to project it to our local projection in our country which is "PRS92" .

I did create an XML of the parameters and paste in manifold config folder.

then i check it from manifold image servers(virtual earth) , and the result was i think not correct.

is there a problem in my XML? or the parameters i used was not fit for this sofware?

Thank you in advance, godbless

Attachments:
PRS.jpg
PRS92-PTM.xml

mao90210
75 post(s)
#27-Sep-18 03:48

Official PRS92 Transformation Parameters

For GPS users, the following transformation parameters will be necessary when undertaking local surveys. They relate the WGS84 Datum, to which all GPS data is referenced to PRS92 on the Luzon Datum. These parameters are applied to WGS84 geocentric cartesian coordinates to give cartesian coordinates of the PRS92 datum which will then be transformed to geographical PRS92 coordinates.

Transformation parameters (WGS84 to PRS92):

Delta X = 127.62153 meters

Delta Y = 67.24339 meters

Delta Z = 47.04738 meters

Rot X = -3.06803 seconds

Rot Y = 4.90297 seconds

Rot Z = 1.57807 seconds

scale parameter = 1.06002

Transformation parameters (PRS92 to WGS84):

Delta X = -127.622 meters

Delta Y = -67.245 meters

Delta Z = -47.0433 meters

Rot X = 3.068 seconds

Rot Y = -4.903 seconds

Rot Z = -1.578 seconds

scale parameter = -1.06002

The general similarity transformation formula that relates two sets of coordinates is shown below:

adamw


8,259 post(s)
#27-Sep-18 09:40

The XML, as written, specifies rotation factors in degrees, and they should be in seconds. You can either convert values to seconds, or specify the unit:

#

...

  <rotationX unit="arcsec">-3.068...</rotationX>

  <rotationY unit="arcsec">4.902...</rotationY>

  <rotationZ unit="arcsec">...

...

(Ignore the leading #, it's there for the forum highlighter.)

If this does not solve it, post a coordinate, the wrong values it converts to using the datum and the values you expect it to convert to.

mao90210
75 post(s)
#27-Sep-18 11:15

Thank you for your reply adamw.

I did follow your instructions, but the projection was almost closer for about 200m. but not quite.

These are an example of my coordinate im trying to convert.

from prs92 geographic coordinates = long 125-39-3.00392, lat 7-10-44.24165 equivalent

also to prs92 Grid coordinates = N793810.517, E571885.088

equivalent to wgs-84 geographic coordinates = long 125.39085171463, lat 7.10410948685

Im attaching a map file for your reference..

Thank you very much

Attachments:
s1.jpg
s2.jpg
sample.map

adamw


8,259 post(s)
#27-Sep-18 16:12

Thanks.

Things seem good, you just have to specify the parameters that convert from PRS92 to WGS84, not the other way around (the XML in the first post specifies the parameters from the wrong set). I should have spotted this on the first run - the convention is to specify the parameters for the transform *to* WGS84.

mao90210
75 post(s)
#28-Sep-18 06:15

Wow, Thank you Very much! now it perfectly works

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