GEOMAP function in the Middle East – shift.

[ScotBIM]

This issue is related to another issue I posted recently regarding the transformation of ESRI data from one zone to another in the MAP3D forum, and now with this issue I am losing faith here...

We have received survey data from our client that is validated and checked by an independent survey company and set to the Saudi Arabian, “Ain El Abd” grid. The site is on the west coast of the Arabian Peninsula and related to UTM37N.

However when I use the GEOMAP function and bring in the background aerial photograph from Bing -  this shows a shift of over 2Km, see attached screen grab; 01_AinelAbd37Nplan. My settings for “Ain El Abd” can be seen in the attachment; 02_AinelAbd37Nsettings. The two objects in red are an existing earthworks and the blacktop area around a small electrical substation.

We have been using GEOMAP effectively on other projects around Saudi Arabia, on UTM WGS84, specifically on the east coast using UTM39N – so out of interest I changed the drawing settings to UTM WGS84 -37N and although we still have an unacceptable shift, this time it is only 125 metres. Nevertheless this is of course still not acceptable – see attached screen grab; 03_UTM37Nplan.

[ScotBIM]

After spending some time today looking at different options, I am further confused...

Disregarding the data we received from the surveyors, I did a check between different online mapping and conversion tools >>>>

I used both Google Maps and then rechecked again using Earth Point and latlong.net to determine what the Latitude and Longitude of the centroid of that squarish earthwork was - which by eye was: 22.328261 / 39.114044

Now back in Civil3D, set to UTM/WGS84/37N (see attached file 04_UTM37Nsettings), the fifth attachment (05_UTM84-37Ncheck) shows that point input (and  labelled) in Civil3D, which is approximately 30 metres shifted to the left. Hmmmm . . . . . .