• EN
Solved

ESRIReprojectot vs Reprojector

sigtill
Rank
Badge +21

When I use the Reprojector:

The coordinate system seems to be correct:

Coordinate System Parameters

CS_NAME: UTM31-ED50 DESC_NM: Universal Transverse Mercator Zone 31 North (Europ50) DT_NAME: EUROP50 GROUP: EUROPE MAP_SCL: 1 PARM1: 3 PROJ: TM QUAD: 1 SCL_RED: 0.9996 UNIT: METER X_OFF: 500000 Datum Parameters DELTA_X: -87 DELTA_Y: -98 DELTA_Z: -121 DESC_NM: European 1950, mean Values ELLIPSOID: INTNL SOURCE: US Defense Mapping Agency, TR-8350.2-B, December 1987 USE: MOLODENSKY Ellipsoid Parameters DESC_NM: International - 1924 E_RAD: 6378388 P_RAD: 6356911.9461279465 SOURCE: US Defense Mapping Agency, TR-8350.2-B, December 1987 OGC WKT Description PROJCS["Universal Transverse Mercator Zone 31 North (Europ50)", GEOGCS["ED50", DATUM["European_Datum_1950", SPHEROID["International - 1924",6378388,297.0000000000014, AUTHORITY["EPSG","7022"]], AUTHORITY["EPSG","6230"]], PRIMEM["Greenwich",0], UNIT["degree",0.0174532925199433], AUTHORITY["EPSG","4230"]], PROJECTION["Transverse_Mercator"], PARAMETER["latitude_of_origin",0], PARAMETER["central_meridian",3], PARAMETER["scale_factor",0.9996], PARAMETER["false_easting",500000], PARAMETER["false_northing",0], UNIT["METER",1]] Esri WKT Description PROJCS["Universal_Transverse_Mercator_Zone_31_North_Europ50",GEOGCS["GCS_European_1950",DATUM["D_European_1950",SPHEROID["International_1924",6378388,297.0]],PRIMEM["Greenwich",0],UNIT["Degree",0.017453292519943295]],PROJECTION["Transverse_Mercator"],PARAMETER["latitude_of_origin",0],PARAMETER["central_meridian",3],PARAMETER["scale_factor",0.9996],PARAMETER["false_easting",500000],PARAMETER["false_northing",0],UNIT["Meter",1]]

However when I examine the data the data is off approx 3m in the x-direction.

 

I try to use the ESRIReprojector instead selecting:

However when I then examine the coordinate system it seems to be the wrong one and in degrees rather than meter:

Coordinate System Parameters

CS_NAME: _LLERP50-W_0 DESC_NM: Lat/long referenced to European 1950 ala Multiple Regression DT_NAME: ERP50-W ESRI_WKT: GEOGCS["GCS_European_1950",DATUM["D_European_1950",SPHEROID["International_1924",6378388.0,297.0]],PRIMEM["Greenwich",0.0],UNIT["Degree",0.0174532925199433]] GROUP: LL MAP_SCL: 1 MAX_LAT: 90 MAX_LNG: 180 MIN_LAT: -90 MIN_LNG: -180 PROJ: LL QUAD: 1 SCL_RED: 1 SOURCE: Datum from DMA TR-8350.2-B UNIT: DEGREE ZERO_X: 1.0000000000000003e-9 ZERO_Y: 1.0000000000000003e-9 Datum Parameters DELTA_X: -87 DELTA_Y: -96 DELTA_Z: -120 DESC_NM: European 1950, Western Europe ELLIPSOID: INTNL SOURCE: US Defense Mapping Agency, TR-8350.2-B, December 1987 USE: MULREG Ellipsoid Parameters DESC_NM: International - 1924 E_RAD: 6378388 P_RAD: 6356911.9461279465 SOURCE: US Defense Mapping Agency, TR-8350.2-B, December 1987 OGC WKT Description GEOGCS["Lat/long referenced to European 1950 ala Multiple Regression", DATUM["European_Datum_1950_1977", SPHEROID["International - 1924",6378388,297.0000000000014]], PRIMEM["Greenwich",0], UNIT["degree",0.0174532925199433]] Esri WKT Description GEOGCS["GCS_European_1950",DATUM["D_European_1950",SPHEROID["International_1924",6378388.0,297.0]],PRIMEM["Greenwich",0.0],UNIT["Degree",0.0174532925199433]]

It also gives an error in the logfile:

Coordinate system named _SPHERICAL_MERCATOR_1 does not exist.

But I can not seem to figure out the mistake. Any help?

icon

Best answer by daveatsafe 17 October 2018, 19:31

View original
The real SigTill

10 replies

bruceharold
Rank
Badge +16

Hi, your target CS uses International 1924 spheroid and you're specifying source data in geographic WGS84 in Reprojector and projected Web Mercator (3857) in EsriReprojector, they are different. A datum transformation is needed and offered in EsriReprojector, just get the source CS and transformation direction right. CSMapReprojector offers a datum transformation too. I find sometimes projection gets tricky and takes some experimentation. Dynamic datums are coming so we'll be monitoring epochs (timestamps) some time too.

sigtill
Rank
Badge +21

Hi, your target CS uses International 1924 spheroid and you're specifying source data in geographic WGS84 in Reprojector and projected Web Mercator (3857) in EsriReprojector, they are different. A datum transformation is needed and offered in EsriReprojector, just get the source CS and transformation direction right. CSMapReprojector offers a datum transformation too. I find sometimes projection gets tricky and takes some experimentation. Dynamic datums are coming so we'll be monitoring epochs (timestamps) some time too.

Hi! Thanks a lot for the quick reply. I did start out with the CSMapReprojector also. If I use these settings then the result is "even worse" but at least different.

 

 

 

The real SigTill
P

Several problems here, this is typical in the North Sea and various transformations (methods and parameters) are offered by Esri corresponding to the EPSG database (see epsg.io)

Reprojector:

 

You are reprojecting from "WGS84 lat, long" to ED50 UTM31 with zero knowledge of the datum transformation

ESRI Reprojector:

 

If source data are EPSG:4326 you should specify GCS_WGS_1984 as the source reference system.

 

Guess destination should still be ED50 UTM31...

 

And You MUST have a look at epsg.io to choose the correct transformation parameters. And as @bruceharold writes CS might also be an option.

In the old days there could be a specific datum transformation for each survey, field, well etc. But this was not well documented and various software treated this stuff differently.

sigtill
Rank
Badge +21

Several problems here, this is typical in the North Sea and various transformations (methods and parameters) are offered by Esri corresponding to the EPSG database (see epsg.io)

Reprojector:

 

You are reprojecting from "WGS84 lat, long" to ED50 UTM31 with zero knowledge of the datum transformation

ESRI Reprojector:

 

If source data are EPSG:4326 you should specify GCS_WGS_1984 as the source reference system.

 

Guess destination should still be ED50 UTM31...

 

And You MUST have a look at epsg.io to choose the correct transformation parameters. And as @bruceharold writes CS might also be an option.

In the old days there could be a specific datum transformation for each survey, field, well etc. But this was not well documented and various software treated this stuff differently.

Hi, thanks a lot for the quick reply!

 

https://epsg.io/1612 and https://epsg.io/1613 is the "goal" and I do have example data to compare with as the "solution"

 

 

The real SigTill
lars_de_vries
Badge +10

I have been searching the Esri projections and I found the "ED50 TM 0 N". I compared it with the parameters of the FME UTM31-ED50 and they seem to match.

The Destination system you chose, starts with GCS which per definition is a Geographic Coordinate System, and not a Projected Coordinate System, describing the sphere and thus in decimal degrees and not in meters.

Hope this helps.

daveatsafe
Rank
Userlevel 2
Badge +17

Hi @sigtill,

There is a key difference between the Reprojector and the CsmapReprojector interface - in the Reprojector, the existing coordinate system on the input data will override the source coordinate system. In the CsmapReprojector and EsriReprojector, the reverse is true - the source coordinate system you choose will override coordinate system set on the source data.

When you use the Reprojector, the source data is properly reprojected from the existing source coordinate system to UTM31-ED50. However, you have no control over the datum transformation used - it will be FME's default. The datum transformation used for your example data may have been different.

I would recommend examining your source data in the Data Inspector to see what the source coordinate system is. Enter this as the source coordinate system in the CsmapReprojector, then set the output coordinate system as desired. The Transformation input will now have a list of available transformations between the two datums. Pick the one that matches the desired transformation.

This is also the procedure you would use with the EsriReprojector, except that the source coordinate system name will be different, so you need to check that it is equivalent to that shown in the Data Inspector. Esri usually has a more extensive choice of transformations than Csmap, so you may have better luck finding a match.

sigtill
Rank
Badge +21

Hi @sigtill,

There is a key difference between the Reprojector and the CsmapReprojector interface - in the Reprojector, the existing coordinate system on the input data will override the source coordinate system. In the CsmapReprojector and EsriReprojector, the reverse is true - the source coordinate system you choose will override coordinate system set on the source data.

When you use the Reprojector, the source data is properly reprojected from the existing source coordinate system to UTM31-ED50. However, you have no control over the datum transformation used - it will be FME's default. The datum transformation used for your example data may have been different.

I would recommend examining your source data in the Data Inspector to see what the source coordinate system is. Enter this as the source coordinate system in the CsmapReprojector, then set the output coordinate system as desired. The Transformation input will now have a list of available transformations between the two datums. Pick the one that matches the desired transformation.

This is also the procedure you would use with the EsriReprojector, except that the source coordinate system name will be different, so you need to check that it is equivalent to that shown in the Data Inspector. Esri usually has a more extensive choice of transformations than Csmap, so you may have better luck finding a match.

Thanks for the fast reply @DaveAtSafe ! I thought I had tried all the options on the CsmapReprojector - but I guess not. I`ll post back here when I get to try it a bit more later tonight.

 

 

The real SigTill
P
Hi, thanks a lot for the quick reply!

 

https://epsg.io/1612 and https://epsg.io/1613 is the "goal" and I do have example data to compare with as the "solution"

 

 

@sigtill you may have a hard time to get exactly the same results as your example data if these have been transformed from WGS84 to ED50 in the past and the transformation (method and parameters) are not documented :/ Good luck!

 

sigtill
Rank
Badge +21

EUREKA! Just had to post the final solution. After great help from you, the client and the people at Norkart! The solution was to use the ESRIReprojector with the following settings!

The real SigTill
P

EUREKA! Just had to post the final solution. After great help from you, the client and the people at Norkart! The solution was to use the ESRIReprojector with the following settings!

@sigtill, nice! Did You try GCS_WGS_1984 also, would be nice to know if the results are the same as using the "auxiliary sphere" as source SCS.

 

Reply


Community Stats

28,866
Posts
109,982
Replies
36,671
Members
Terms & ConditionsCookie settings
A product of
Safe Software respectfully acknowledges that we live, learn and work on the traditional and unceded territories of the Kwantlen, Katzie, and Semiahmoo First Nations.