1

i did a custom projection ITM (Israel TM) and i then am doing transform to all the feature before im adding them to the map, from ITM to 900913 proj because i want to show the feature on the map. this is the string for the ITM proj:(i am using it with proj4js)

+proj=tmerc +lat_0=31.73439361111111 +lon_0=35.20451694444445 +k=1.0000067 +x_0=219529.584 +y_0=626907.39 +ellps=GRS80 +towgs84=-48,55,52,0,0,0,0 +units=m +no_defs 

but, when i add the feature like this:

            features.geometry.transform(ITM, proj900913);
            vectors.addFeatures(features);

the feature is place 4 meter to the north and 4 meter to the east, and not in the place its suppose to be. its also happening when i am load KML layer.

how can i place the point in the right place? thx

  • I think this is pretty reasonable transformation accuracy. – BradHards Jul 11 '13 at 10:12
  • there is a way to fix it? – Jordan Jul 11 '13 at 15:02
1

From what I know, very accurate transformations are available from the Survey of Israel, but they are not publicly available. I don't know the accuracy or source of this transformation. It's in ArcGIS with the following direction, method, and parameter values. PROJ4 uses position vector (different rotation convention so all rotation signs have to be changed) and wants to WGS84 not from WGS84, so all parameter signs need to be changed).

WGS84 to Israel
Coordinate Frame
X Axis Translation = -24.0024
Y Axis Translation = -17.1032
Z Axis Translation = -17.8444
X Axis Rotation = -0.33009
Y Axis Rotation = -1.85269
Z Axis Rotation = 1.66969
Scale Difference = 5.4248

Israel to WGS84
Position Vector
X Axis Translation = 24.0024
Y Axis Translation = 17.1032
Z Axis Translation = 17.8444
X Axis Rotation = -0.33009
Y Axis Rotation = -1.85269
Z Axis Rotation = 1.66969
Scale Difference = -5.4248

which converts to

+towgs84=24.0024,17.1032,17.8444,-0.33009,-1.85269,1.66969,-5.4248

  • thanks for your answer, but its didnt fix it, i guess its cant be accurate like i need... – Jordan Jul 13 '13 at 19:55

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.