Move Objects to Specific Coordinates
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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.
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.
Chicagolooper
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
Blaine Young
Senior Engineering Technician, US Army
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).
Chicagolooper
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
Blaine Young
Senior Engineering Technician, US Army
Chicagolooper
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?
Chicagolooper
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.
Chicagolooper
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.
Chicagolooper
