How to apply user defined geodetic transformation

[Anonymous]

Hello,

I'm using autodesk map 3d 2013, and I have created my own coordinate systems and the geodetic transformation between them.

So when i try to change the coordinate system of a drawing the results are far from good (around 300 000 meters in x axis).

Where do I select which transformation will be used?

[Alfred.NESWADBA]

Hi,

>> So when i try to change the coordinate system of a drawing

What data do you have in the drawing, if it's FDO connected like SHP or SDF I can understand the question.

If you have plain AutoCAD geometry in the drawing (like lines, polylines, block-insertions) then assigning a new coordinate system does not change anything in the drawing. A line starting at 10,10 and ending at 20,20 will stay at these xy-values without even knowing that there might be changed a coordinate system.

If you need to transform AutoCAD geometry from one coordinate system to the ohter you have to use the ADE-functionality (described >>>here<<<). During the described querying you the coordinate transformation can be done when the source drawing has another coordsystem than the destination drawing.

HTH, - alfred -

[Anonymous]

Yes I have dwg (line, polylines, points...), and I've done exaclty that, using query (assign coordinate system to original, close it, open new, assign coordinate system to new dwg, attach dwg, run query).

The coordinates of resulting lines, polylines are way off as I said.

I think Map uses only it's built in transformations.

I've also tried assigning those default coordinate system that come with map 3d, but it didn't use geodetic transformation that I have created, rather the bulit-in one.

Again the results were better, but not good enough. This time it was around 3 meters off.

So, where do I have to choose which transformation will be used?

[Alfred.NESWADBA]

Hi,

>> I think Map uses only it's built in transformations.

If that is what you think (about the ADE-functionality) you can verify it: use MAPEXPORT to export your original polylines and points using the original CS, export the data to SDF

Then create a new drawing, use ADESETCRDSYS to assign your new CS and then command _MAPCONNECT to connect to the SDF ... is that now ok?

- alfred -

[Anonymous]

Hi Alfred

I'm sorry to report but, still not good.

I'm wondering what is the point of creating geodetic transformations when i can't use them.

Is there a some king of setting in query which will enable user defined geodetic transformation.

[Alfred.NESWADBA]

Hi,

>> Is there a some king of setting in query which will enable user defined geodetic transformation

No, there is no extra checkbox for "don't use it" (or vice versa).

I would now start command _MAPTRACKCS, configure it to show some different coordinate systems (also yours) that are valid for your geographic area and see which ones are correct (with some points that are officially tested) and which ones not.

Without knowing your settings (your new CS) and also not having reference points (from a trustworthy official source) I can't verify why you get a 3m distance.

- alfred -

[parkr4st]

presumptions:  the data is correctly positioned on the first CS, if it isn't it will be off no matter what you try, double check it

                        the new CS is correct in setup, double check that all the info is correct, a decimal in the wrong place, dropped zero, extra zero, etc

                        you have known points that you have confirmed both cs against so you are sure they are correct to use

                        quite often an overlook of a minor detail will screw up things alot

Dave