topic Re: Move Objects to Specific Coordinates in AutoCAD Forum

Move Objects to Specific Coordinates

richardmorris1969 — Tue, 11 Sep 2018 21:07:41 GMT

I havve an object (a block of houses issued by a designer including dimensions and national grid coordinates of certain points noted. This drawing is not set to these coordinates just noted with them

How do I move the object / drawing to the noted coordinates in order that I can then use it in my survey instrument to set out the building on site.

i think i know how to move it all as a single object and get one point correct but it really requires two points on the object to be moved so that the drawing / object is at correct coordinates and correctly aligned.

Does that make sense?

Thanks in advance all

Re: Move Objects to Specific Coordinates

Kent1Cooper — Tue, 11 Sep 2018 21:13:25 GMT

Welcome to these Forums!

Sounds like a perfect job for the ALIGN command, which can move and rotate-to-correct-alignment in one operation. Read about its use in Help.

Re: Move Objects to Specific Coordinates

ChicagoLooper — Wed, 12 Sep 2018 00:04:25 GMT

Unfortunately the "block of houses" you received from the designer is "not set to these coordinates just noted with them" raises some big issues and I'm not sure you fully understand the implications of those issues. If, and only if, the designer's drawing conforms to the following conditions:

The houses are accurately drawn without any doubt regarding their positions relative to one another.
The designer used a known 'projected' coordinate system and not a 'geographic' coordinate system (the former uses x/y coordinates with units in feet or meters while the latter uses latitude/longitude coordinates in units of degrees).
You have at least two georeferenced points and their coordinates. Without their coordinates the points are useless.

I'm curious as to what the national grid is and how the designer described it.

Re: Move Objects to Specific Coordinates

richardmorris1969 — Wed, 12 Sep 2018 10:40:18 GMT

Thank you guys I will try and use the align tool and then check back using known physical features.

The drawings are accurately drawn within 5mm which I believe will be ok for this type of construction.

The designer is referring to WGS84 system

I dont have two points just the corners of the building i think i will create two points in the position i require and then move / align the building to them

So for example if i had a square of 10m x 10m and one corner was noted as being at coords E 10 N10 and another corner at E10 N20 but were in an arbitrary position.

I propose to create one point at E10N10 and another at E10 N20 and move drag align the relevant corners of the building to those points.

What do you think?

Re: Move Objects to Specific Coordinates

beyoungjr — Wed, 12 Sep 2018 11:32:11 GMT

Hi,

When using the Align command just be careful not to scale the result, you will see the prompt for scaling as Y/N.

Also, If you know which direction true north is in the provided plan then the simplest Align method would be to create a 90 degree line in AutoCAD starting at your known coordinate point and proceeding any length at all (90 degrees being true north in ACAD).

Using the 2 known point of your source objects you can select the first source point, then first target point (start of 90 degree line), then second source point, then second target point (length not important at all). You will then be prompted for scaling Y/N before the alignment is applied. The length can be as short as a centimeter or as long as 200 kilometers because you will not be scaling.

BTW... Please ensure you are working in the WCS before this. Should be unless you have been playing around with coordinate systems.

Hope this helps,

Blaine

Re: Move Objects to Specific Coordinates

ChicagoLooper — Wed, 12 Sep 2018 13:16:14 GMT

When a drawing has been moved out of its correct georeferenced location and you need to move it back using known coordinates as basepoints, you must always scale and rotate as needed in order to ‘force’ the points to match their ‘true’ surveyed position. By ignoring both scale and rotate options within the ALIGN procedure, you are using it as if it were the MOVE command and have effectively marginalized the align command’s soul purpose. This is especially true when a former user has physically moved the line work, for whatever reason, closer to the origin and has rotated the line work a few degrees, however small or unnoticeable, in order to give the drawing a better appearance when printed.

The diagnosis that this drawing has been accidentally ‘nudged’ a few feet or meters out of position is a poor one. Without honoring both scale AND rotate parameters you will definitely get one point accurate and you may, or may not, get the other.

The World UCS orientation is a valid one. Keep in mind that even though north may not point ‘straight up’ it may still indeed, be in world UCS (as is the case when the UCS itself was rotated).

Re: Move Objects to Specific Coordinates

beyoungjr — Wed, 12 Sep 2018 14:09:25 GMT

Did you read anything in my post about "nudged"? Did you read that I suggested an unspecified line length by which to align true north?

If the user was to attempt my proposal the result could get scaled slightly or drastically. My suggestion was as you wrote... ONLY to move and rotate the entire set of objects to the desired location and orientation. All size data would be retained.

If scaling were a crucial part of the Align command it would not be offered as an option! I've been using Align with and without scaling for 15 years or more.

Blaine

Re: Move Objects to Specific Coordinates

ChicagoLooper — Wed, 12 Sep 2018 15:41:29 GMT

Whenever a drawing in taken out of its georeferenced position, it should be scaled and rotated to get it back to its original orientation. Whether the scaling is a lot, drastic or barely noticeable, it should done. There situations when scaling and rotating will mot make a difference but it still should be performed anyway. To suggest that it not be done is misleading.

Re: Move Objects to Specific Coordinates

RobDraw — Wed, 12 Sep 2018 16:41:36 GMT

@ChicagoLooper wrote:
Whenever a drawing in taken out of its georeferenced position

This is key as most of the time those drawings have been broken from their original state. Getting the file from its source in its original state would be ideal. I've had to brake these files many times and normally would just change the units and the coordinate system to suit our needs. I've never had to put them back, and if I did, I always had the original files.

I have a question. Wouldn't it make sense to change the units and coordinate system to what they would be in the original file, than messing around with moving, scaling, and rotating?

Now, if someone hacked those files out of ignorance, there might not be an easy fix.

Re: Move Objects to Specific Coordinates

ChicagoLooper — Wed, 12 Sep 2018 21:04:19 GMT

Yes, absolutely. I agree about the units but I have found many times, too often in fact, where the coordinate system wasn't honored and the drawn line work was physically moved closer to the origin because the user was either uncomfortable, inexperienced, or both, working so far away from 0,0. Plus, with many fingerprints on a drawing, a user may rotate the drawing so it's easier-to-read or to make-it-a-better-fit when viewed through the viewport. These actions cannot be resolved by simply changing the units, due to the GeoRef being broken. I will always defer to a known coordinate system and unit adjustment vs. the align command but doing so may not always be possible.

As it is, this OP is in plain vanilla AutoCAD and not in the C3D or M3D forum so speaking about coordinates may not be applicable to his or her workflow when compared to the workflow typically found in Civil or Map. Even if the coordinates are shown in mtext notes within the drawing, we still don't know whether orientation has been maintained or rotated. All we know is the object, such as a benchmark, building corner, manhole cover, etc, has coordinates that are not consistent with what's displayed in the properties palette.

In the absence of the original drawing file (most likely created by someone with an understanding of coordinate geometry i.e. surveyor, GIS analyst, cartographer, ship navigator, etc.) the align command, or something similar, must be utilized to re-georeference it. This entails 1) re-positioning, 2) rescaling, and 3) rotating. Make no mistake, you need all three. Sometimes rescaling and rotating will have no effect because it already has the correct scale and rotation but performing all three anyway will insure proper alignment. Re-georefing must be done using at least two known points, such as two benchmarks with known coordinates, but using more than two would invariably improve accuracy and the align command is capable of using more than two even though many users only use the minimum.

Regarding known coordinates in the drawing, if you're lucky, they are x- and y-projections measured in units of feet or meters. If the coordinates are not projected but are geographic, then the coordinates are latitude/longitude and are in units of degrees. Would you, and everyone else in your firm, feel confident locating lat/long benchmarks in your drawing when everything else, i.e. buildings, roads, infrastructure, etc. is drawn using feet or meters?

Re: Move Objects to Specific Coordinates

RobDraw — Wed, 12 Sep 2018 22:12:51 GMT

@ChicagoLooper wrote:
Would you, and everyone else in your firm, feel confident locating lat/long benchmarks in your drawing when everything else, i.e. buildings, roads, infrastructure, etc. is drawn using feet or meters?

Maybe you missed the part where I said I've broken these drawings many times. I can only speak for myself and the majority of users at the firms that I've worked at and the simple answer is, "No, we would not feel comfortable." That is only because most of us have never had to do anything like that. Some of us, including me, would love the challenge though. I always had a back-up plan when I broke them, just in case. I always kept the original file. I also made my changes minimal and logical because most likely the file would need to be updated and possibly by someone else.

Re: Move Objects to Specific Coordinates

ChicagoLooper — Wed, 12 Sep 2018 22:54:50 GMT

Sorry, no. I did not miss that part, I'm sorry if I gave that impression. I also didn't miss your question in the second paragraph of Post #9:

@RobDraw wrote:
I have a question. Wouldn't it make sense to change the units and coordinate system to what they would be in the original file, than messing around with moving, scaling, and rotating?

The answer: No, it wouldn't make sense to merely change units and CS, at least not to me because there would be no way to verify accurate position, scale and rotation after the changes are made, whereas with the ALIGN command, I could.

Re: Move Objects to Specific Coordinates

RobDraw — Wed, 12 Sep 2018 23:57:18 GMT

@ChicagoLooper wrote:
The answer: No, it wouldn't make sense to merely change units and CS, at least not to me because there would be no way to verify accurate position, scale and rotation after the changes are made, whereas with the ALIGN command, I could.

So, I, as a user that realizes the civil world is a world and not a project, doing this for the first time would question any workflow that could not be verified after execution.

How do I verify the results after using the ALIGN command and why couldn't that same verification process be applied to any other methodology of fixing those broken files? Furthermore, if having the georeference a requirement of the project, why isn't an accurate version of the civil file available?

Re: Move Objects to Specific Coordinates

ChicagoLooper — Thu, 13 Sep 2018 07:26:01 GMT

After careful thought you could do it using two known points but it wouldn't be as efficient as using the ALIGN command. And yes, you could indeed do it and verify the two point locations as long as you perform all three of these commands during the process:

ROTATE objects
SCALE objects
Physically MOVE objects

Using the ALIGN command, however, would perform all three simultaneously.

Here's a youtube VIDEO that shows how the align command works when combined with known points. The presenter uses two known circle locations instead of two known coordinate points. He could have easily used two pairs of coordinates had they been available, but since none were, he substituted with circles. He also used an aerial photo but he could have used a group of parcel boundaries as well. The video clearly demonstrates the efficiency and effectiveness of the align command. Even though it appears that rotation wasn't needed, the align command insures that if one was required that it would have been performed and not ignored. For verification, he used a visual inspection as opposed to a checking coordinates. If more than two points were used to position the aerial photo and if coordinated values were used instead of circles, then it's likely the accuracy of the ALIGN would have been even better.

To watch the video click >>HERE<<. The pertinent footage demonstrating the align command is 1:10 to 3:50.

Re: Move Objects to Specific Coordinates

RobDraw — Thu, 13 Sep 2018 11:19:09 GMT

So, even though I told you that I didn't use move, scale, or rotate to make the file usable for us, you are telling me that I have to use one of your two methods to put my file back to its original state.

Sorry, but you are wrong. Be careful about talking in absolutes.

Re: Move Objects to Specific Coordinates

ssharma_panindia — Thu, 18 Jul 2024 12:40:45 GMT

Can we align the data with four reference point?