Coordinate transformation

[igi_pop]

Hello!

I've been bugging myself with this for a while. SInce i mostly did civil3d (without real MAP utilization), i needed to learn a few - and i did. Autodesk community rocks.

However, i wanted to test it out.

So, i assigned one of my empty drawings a HDKS-5 (croatia, gaus-kruger), drew a CAD point at desired coords.

Made a second empty drawing, assigned a HTRS96 (etrs89), went trough the procedure of attaching a drawing in maptools, querry all objects (one point) and drew them  by "execute querry".

Took the coords from the HDKS and transformed them with the official geodetic system in croatia for comparison.

Civil's result is off by 750m E, and 500m N, roughly. And it does not transform the Z at all, but that's irrelevant in this case.

Any ideas?

maybe i'm missing a basic part of the procedure before attachment?

Thanks in advance!

Kindly, Igor

p.s.

yes, we have a payed access to the official coord transformation, but it requieres a text file of sorts, formated. And i have something like 100 projects with points whose data i would like to keep (excel sheet per project). WIth that in mind, it's much easier to create the points from excel with corresponding data in it's given coord system and just transform it, than it is to go back and forth with copy paste to create the transformation.

[Pointdump]

Igor,

Transformation works different for Civil 3D Objects than AutoCAD Objects. Was the point you were trying to transform a COGO Point or an AutoCAD Point?

Dave

[igi_pop]

Basicaly it's all the same to me. I was trying COGO, but the procedure returned 0 (zero) objects drawn in the new drawing.

So, i drew an ordinary point on the same spot (literaly, snaped to COGO) and did the transformation.

Ideas?

[Pointdump]

Igor,

"Basically it's all the same to me."

Nope. Transforming Civil 3D Objects like COGO Points is different than transforming dumb linework (AutoCAD Objects). Use Attach/Query for linework, but for COGO Points make a new Point File Format that identifies what Coordinate System the points are on.

Dave

[igi_pop]

---

@Pointdump wrote:

Igor,

"Basically it's all the same to me."

Nope. Transforming Civil 3D Objects like COGO Points is different than transforming dumb linework (AutoCAD Objects). Use Attach/Query for linework, but for COGO Points make a new Point File Format that identifies what Coordinate System the points are on.

Dave

---

Thanks Dave!

What i ment was, i don't mind transforming either one of those as the points still don't exist. I'll be creating them. Wether i create regular od COGO is all the same for the, whatever puts me in a good position for transformation 🙂

Thank you for the tip, i will try your suggestion!

Cheers

[igi_pop]

It doesn't work. Does not convert anything to anything. Just keepst the imported coords. I has made something differend when i applied the transformation setting in "drawing properties" but it was off, way off.

When you pick the coord system in the point file type, could it be that it can't transform points to a system that's not listed in the menu?

For instance, our local (and now official) is the HTRS. It can be assigned by MAP, but is not available in the point file list..

And when i go to drawing settings it says "auto registered" on the drop menu.

i'm using blank files with just assigned zones, and it just won't go so far.

Cheers

[sboon]

A couple of things to check:

• Are your formats set to import GRID north and east?
• There is an option at the bottom of the import points dialog to "Do coordinate transformation if possible"  Is that checked on?

Steve
Please use the Accept as Solution or Kudo buttons when appropriate

[Pointdump]

Igor,

HDKS-5 (croatia, gaus-kruger)
HTRS96 (etrs89)

"...our local (and now official) is the HTRS. It can be assigned by MAP, but is not available in the point file list."

I haven't seen that before, but it's certainly possible. Please post that drawing and which version of C3D and Service Packs you're using.

In the Coordinate System Library, I'm guessing HDKS-5 (croatia, gaus-kruger) is CROATIA-5-9. But I can't find HTRS96 (etrs89) in the Library.

And here's some interesting information in the Knowledge Network:

https://knowledge.autodesk.com/support/autocad-civil-3d/troubleshooting/caas/sfdcarticles/sfdcarticl...

When you say "Civil's result is off by 750m E, and 500m N", are you estimating that based on comparing a point's apparent location in Bing Live Maps? 750mEast/500mNorth of what?

Steve makes two excellent and necessary points about transformation in the Point File Formats.

How about posting a "Source" drawing with a point or two, and a "Target" drawing in the Official Coordinate System.

Dave

[autoMick]

Igor, this isn't exactly what you're getting at, but see my idea here: http://forums.autodesk.com/t5/autocad-civil-3d-ideas/account-for-coordinate-system-differences-when-.... At the bottom you'll see reference to ADEQUERY as a command which can be useful [edit: this command may be the equivalent of @Pointdump's suggestion of Attach/Query above]

Cheers

- Mick

[igi_pop]

I'll refer to all of your posts now..

---

A couple of things to check:

• Are your formats set to import GRID north and east?
• There is an option at the bottom of the import points dialog to "Do coordinate transformation if possible"  Is that checked on?

Steve

---

1st - no. i just assigned to import ENZ, honestly did not occur to me that it should be grid. Should it??

2nd - i've tried with and without, and it just did not convert at all. It would simply bring in that one point to it's HDKS coordinates (that's milions easting versus 100000s that should be in HTRS).

---

@Pointdump wrote:

Igor,

HDKS-5 (croatia, gaus-kruger)
HTRS96 (etrs89)

"...our local (and now official) is the HTRS. It can be assigned by MAP, but is not available in the point file list."

I haven't seen that before, but it's certainly possible. Please post that drawing and which version of C3D and Service Packs you're using.

In the Coordinate System Library, I'm guessing HDKS-5 (croatia, gaus-kruger) is CROATIA-5-9. But I can't find HTRS96 (etrs89) in the Library.

And here's some interesting information in the Knowledge Network:

https://knowledge.autodesk.com/support/autocad-civil-3d/troubleshooting/caas/sfdcarticles/sfdcarticl...

When you say "Civil's result is off by 750m E, and 500m N", are you estimating that based on comparing a point's apparent location in Bing Live Maps? 750mEast/500mNorth of what?

Steve makes two excellent and necessary points about transformation in the Point File Formats.

How about posting a "Source" drawing with a point or two, and a "Target" drawing in the Official Coordinate System.

Dave

---

As for your suggestions, Dave:

1. i took one research spot, old project, HDKS-5 (GK 0.99) zone

2. made another drawing and converted the ACAD point (via the attach menu in MAP)

3. took the same point and converted it in the official web-app we have acces to

4. compared results from step 2 and 3

	x	y	z
hdks	5594354,47	5068162,77	102,6
htrs_civil	478032,97	5067480,92	102,6
t7d	477281,09	5067977,90	102,436

So, converting an ordinary point via the attach tool did bring it up at least to the same order of magnitude.

Additionaly, i'm rumaging trough my files, and i noticed i can't find HTRS aswell. So, i opened a drawing and it asked "do i want it in library". So, i picked it up from one of our investors to begin with 😕 no wonder you all could not find it.

Anyways, i've attached a drawing with the coord system assigned and searchable, two snapshots showing the systems. The HTRS drawing will contain nothing, and the HKDS will contain the point of inquiry and the apropriate coord system assigned. The table above, t7d is the official transformation.

So, if anyone finds a procedure to get it within 1m accuracy - i'm getting you all some beer or homemade juice or something 🙂

Oh yea, i'm using an updated 2015 civil. And yes, i REALLY do apreciate your efforts. I'll have a total of close to 1000 points that need be transfered for this project alone (a Feasibility study, exploaration points with added data), and if i could finaly gather the knowlege on these procedures, i could again upgrade our procedures, ease a lot of things related. I'm farely good with civil, and i'd rather have the multifunctionality than writhing up 3 columns of XYZ and converting them. This way, i can pick up anything from the excel file, or CSV. Thanks

[Pointdump]

Igor,

You can change "Auto-Registered" here:

Add it to Coordinate Systems related to Croatia here:

In the "hdks" drawing I exported the point in ENZ(comma delimited):

In the "HTRS" drawing imported that same point by using this Point File Format:

So I get same as you in the "HTRS" drawing:
478032.9684,5067480.9183,102.6000

So at this point, either the coordinate system in the "HTRS" drawing is wrong or table T7D is wrong. Without knowing EXACTLY what coordinate system is your "official" all we can do is guess. So what is the EPSG Number for the official coordinate system?
https://epsg.io/

Dave

[igi_pop]

---

@Pointdump wrote:

Igor,

You can change "Auto-Registered" here:

Add it to Coordinate Systems related to Croatia here:

In the "hdks" drawing I exported the point in ENZ(comma delimited):

In the "HTRS" drawing imported that same point by using this Point File Format:

So I get same as you in the "HTRS" drawing:
478032.9684,5067480.9183,102.6000

So at this point, either the coordinate system in the "HTRS" drawing is wrong or table T7D is wrong. Without knowing EXACTLY what coordinate system is your "official" all we can do is guess. So what is the EPSG Number for the official coordinate system?
https://epsg.io/

Dave

---

T7D in the table - numbers we get when giving it to the state geodetic service/management whatnot. So i gotta go by that 🙂

So i did things right 😄 yaaay! and nay to some extent 🙂

You got me with the epsg number, gonna look into that tomorrow!

Thanks for the tip on assigning a gedetic system to a country!

[igi_pop]

Ok!
Could not let it go..it's mentioned in all GIS files i could dig up for various software (croatian manuals, and so on)

https://epsg.io/3765

I see that some parameters do not match when i go to EDIT. I was wondering, btw, can i edit it at all..

Well, now i know and can toy with the parameters 🙂

If you make the shoe fit with this data - let me know, please. And what did you alter to make it work.

Cheers man, we're narrowing it down thanks to your efforts!

[Pointdump]

Igor,

"Could not let it go..."

Ha ha! Me either.

In your Coordinate System Library pick the CS that is closest to what you need. Use Duplicate, then Edit to plug in all your parameters. (You won't be able to Edit any of the existing Coordinate Systems in the Library, so you have to make a duplicate first.)

PROJCS["HTRS96 / Croatia TM",
GEOGCS["HTRS96",
DATUM["Croatian_Terrestrial_Reference_System",
SPHEROID["GRS 1980",6378137,298.257222101,
AUTHORITY["EPSG","7019"]],
TOWGS84[0,0,0,0,0,0,0],
AUTHORITY["EPSG","6761"]],
PRIMEM["Greenwich",0,
AUTHORITY["EPSG","8901"]],
UNIT["degree",0.0174532925199433,
AUTHORITY["EPSG","9122"]],
AUTHORITY["EPSG","4761"]],
PROJECTION["Transverse_Mercator"],
PARAMETER["latitude_of_origin",0],
PARAMETER["central_meridian",16.5],
PARAMETER["scale_factor",0.9999],
PARAMETER["false_easting",500000],
PARAMETER["false_northing",0],
UNIT["metre",1,
AUTHORITY["EPSG","9001"]],
AXIS["Easting",EAST],
AXIS["Northing",NORTH],
AUTHORITY["EPSG","3765"]]

Dave

[igi_pop]

---

@Pointdump wrote:

Igor,

"Could not let it go..."

Ha ha! Me either.

In your Coordinate System Library pick the CS that is closest to what you need. Use Duplicate, then Edit to plug in all your parameters. (You won't be able to Edit any of the existing Coordinate Systems in the Library, so you have to make a duplicate first.)

PROJCS["HTRS96 / Croatia TM",
GEOGCS["HTRS96",
DATUM["Croatian_Terrestrial_Reference_System",
SPHEROID["GRS 1980",6378137,298.257222101,
AUTHORITY["EPSG","7019"]],
TOWGS84[0,0,0,0,0,0,0],
AUTHORITY["EPSG","6761"]],
PRIMEM["Greenwich",0,
AUTHORITY["EPSG","8901"]],
UNIT["degree",0.0174532925199433,
AUTHORITY["EPSG","9122"]],
AUTHORITY["EPSG","4761"]],
PROJECTION["Transverse_Mercator"],
PARAMETER["latitude_of_origin",0],
PARAMETER["central_meridian",16.5],
PARAMETER["scale_factor",0.9999],
PARAMETER["false_easting",500000],
PARAMETER["false_northing",0],
UNIT["metre",1,
AUTHORITY["EPSG","9001"]],
AXIS["Easting",EAST],
AXIS["Northing",NORTH],
AUTHORITY["EPSG","3765"]]

Dave

---

I made a duplicate, and can only edit as much as the previous one..

Gonna try and create one..

[Pointdump]

Igor,

I compared the custom HTRS96/TM Coordinate System with EPSG:3765 and the only difference is the Datum:
EPSG:3765-DATUM["Croatian_Terrestrial_Reference_System"]
HTRS96/TM-DATUM["WGS84"]

That could certainly account for the difference, but I'm not sure how to verify a transformation between the two datums.

I put that point into QGIS, which recognizes the EPSG:3765, and exporting a shapefile. I drag-n-dropped the new shapefile into a C3D drawing with the custom HTRS96/TM Coordinate System and got closer, but still not the same as T7D:
t7d-- 477281.0900 5067977.9000
3765-- 477261.3747 5067471.6034

Dave

[igi_pop]

T7D is a 7 point trasformation, most likely we won't get closer 😕

I've noticed that MAX-MIN X and Y (probably lat-long as well) are different in the system i had in the library, compared to the online info for EPSG:3765.

That's why i'm trying to create a custom coord system now, but i can't input X Y directly as it seems, i gotta go with lat long, a those numbers are not available on that online site you gave me.

I'll keep diggin'!

[Pointdump]

Igor,

You can certainly define a 7 point transformation between datums in C3D. You just need to know what those 7 numbers are. And then you can change the Datum definition in the custom HTRS96/TM Coordinate System.

Keep digging.

Dave

[igi_pop]

Ok!

It's me again!

Now that i got my Civil(izations) working, what the h are these two? Is it something that gets executed automaticaly when you apply a transformation at import?

Ages ago when i started using civil3d i got a good tip at AU - use the ? mark, it HELPS. But help files are so often just...nothing..."If you press create corridor, you'll be taken to a create corridor wizard" or something 😄

so, what can you tell me about this?

Cheers!

[sboon]

Clicking some of the links in the help files got me to this.

About Geodetic Transformation Paths

Geodetic transformation performs a cartographic transformation from a coordinate reference system to produce a geographic coordinate system (that is, latitude and longitude) that is referenced to the same datum as the source coordinate system. Geodetic transformation paths concatenate individual geodetic transformations to use when a direct transformation is not available.

For example, you might have two drawings: one that uses geographic coordinate system A and one that uses geographic coordinate system C. If you have only transformations for A to B and A to D, there is no direct transformation from A to C. If there is a transformation defined from B to C and from D to C, AutoCAD Map 3D has to choose one of these. It might use the transformation A to B to C. However, you might prefer that it use A to D to C.

To ensure that the transformation path A to D to C is used, define that transformation option as a specific geodetic transformation path. Once you define a path, AutoCAD Map 3D will always use the one you defined. You can add paths that use their original definitions, and you can add the inverse version of the paths.