topic Re: Change to proper coordinate system(QNG) in AutoCAD Forum

Change to proper coordinate system(QNG)

s_manoosmanoos — Wed, 20 Sep 2023 20:28:15 GMT

The drawing i have attached here is not in a proper coordinate system so i have to change it into correct coordinate (QNG)

Re: Change to proper coordinate system(QNG)

paullimapa — Mon, 11 Jul 2022 02:22:33 GMT

doing a search online for QNG coordinates, maybe this will help:

Convert Qatar coordinates - Qatar National Grid (expertgps.com)

Re: Change to proper coordinate system(QNG)

Pointdump — Mon, 11 Jul 2022 08:03:47 GMT

Hi @s_manoosmanoos,
I read the notes carefully, but they just don't make sense.
Subtracting (moving the drawing coordinates) by E:227974.450, N:347213.411 won't work. And there is a baffling custom UCS applied. Can you post the XREF's, particularly "Plot Plan" and "Plot Plan - 1"?
Dave

Re: Change to proper coordinate system(QNG)

s_manoosmanoos — Wed, 20 Sep 2023 20:28:52 GMT

Thanks Sir...! but there is no plot plan given by client however I have aligned the drawing to the correct location but not sure is aligned properly or not?

please I have attached the drawing for your reference.

Re: Change to proper coordinate system(QNG)

Pointdump — Mon, 11 Jul 2022 17:40:21 GMT

@s_manoosmanoos,
You got farther along than I did. Looks good.
Dave

Re: Change to proper coordinate system(QNG)

richard_387 — Mon, 11 Jul 2022 19:12:38 GMT

Do you want to keep the drawing in its current alignment, i.e. with the units in millimetres and the coordinates with the Eastings increasing up the page and the Northings increasing to the left hand side?

Your posted drawing has the units in metres and the coordinates going in the conventional directions.

Your first posted drawing has a UCS called PLANT NORTH. If you draw a line to 0,0 in the UCS system and then a line from there @-227974450,-347213411. This gives the zero point of the QNG. Now set up a new uCS using this point as zero and aligned as previously and save it as QNG. Now you have two UCSs which you can change as necessary, but remember the units are millimetres, and the drawing is as it was before.

Re: Change to proper coordinate system(QNG)

Michiel.Valcke — Tue, 12 Jul 2022 14:05:41 GMT

This looks like an ortho drawing generated from AutoCAD Plant 3D, but then printed as a .pdf and reinserted into a .dwg

If that is the case then the North/East references in your views do not correspond to real word coördinates but to the plant origin point (or even another, sub north point). In Plant 3D the design is done as close to the origin as possible. Also in other CAD programs it is good measure to design close to your origin.

If you really need to line out the .dwg onto it's real-world reference I would recommend using a program like AutoCAD Map3D or Autodesk Civil3D. There you can assign the correct coördinate system with the command MAPCSASSIGN

Then you can use the command GEOMAP to project the bingmaps satelite imagery on the background of your drawing.

It looks like you got very close indeed.

You can use the command Adersheet to further align your dwg to recognizable points in the background image. If you have a better background (like a WMS service) you can more accurately determine its position. but you'll always have to fiddle around with it unless your client gives you the original Plant 3D dwg (not the ortho) with the 3D geometry and the correct transformation values (for x,y,z and rotation).

Re: Change to proper coordinate system(QNG)

s_manoosmanoos — Tue, 23 Aug 2022 18:46:35 GMT

Thanks for your reply Mr Michel Valcke and all you who respond to this thanks.
however, there is a funny thing is in this case that The drawing I received from the client has been mistakenly moved to another location. so it is found and sort it out in the meeting and they accepted their fault.