Misplaced Xref

[AllenJessup]

An Engineer created a design drawing and Xrefed the survey basemap. He asked me to create and Acquisition map based on the design. I started a new drawing and Xrefed both the basemap and the design drawing. They didn't line up.

I found the Xref in the Design drawing is shifted. I checked the usual things. Both Xrefs are inserted an 0,0,0 at a 1 scale. The Base in both drawings are 0,0,0. The units and State Plane coordinates in both drawings are the same. "Scale Objects inserted from other drawings" is not checked in either drawing.

Working in a copy of the Design drawing. I inserted the basemap again. It inserted at the "correct" position. I can list both separately and both insertion points are 0,0,0 at a 1 scale. But the new Xref doesn't overlay the first one. The displacement is 2.043'. In the Xref Manager the Xref is only listed once and if I select the drawing in the Xref Manger it selects both versions of the Xref.

I know I'll have to reattach the basemap in the design drawing and move all the design to match. A pain but that's what I'll have to do. But I don't understand how I can have 2 versions of the same drawing Xrefed at 0,0 and not have them line up.

Has anyone seen this or have an idea on how it happened? I'll attach a PDF showing some of the checks I've done.

[MMcCall402]

Any chance there is a XY scale or rotation error in the problem xref insertion that is so small that its not showing up in the limited listed precision. At 600-800k from the origin wouldn't take much to mess it up.

[user181]

Is it possible the system variable INSBASE isn't set to 0,0,0 in all the drawings?

[AllenJessup]

Nothing shows within the limits of the program.

                  BLOCK REFERENCE  Layer: "Xref SMSR"
                            Space: Model space
                   Handle = 183f2
       Block Name: "Smsr"
                  External reference
                at point, X=0.00000000  Y=0.00000000  Z=0.00000000
   X scale factor: 1.00000000
   Y scale factor: 1.00000000
   rotation angle: 0d0'0.0"
   Z scale factor: 1.00000000
         InsUnits: Feet
  Unit conversion: 0.99999800
  Scale uniformly: No
  Allow exploding: Yes

Command:
LIST

Select objects: 1 found

Select objects:

                  BLOCK REFERENCE  Layer: "Xref Re SMSR"
                            Space: Model space
                   Handle = 348a5
       Block Name: "Smsr"
                  External reference
                at point, X=0.00000000  Y=0.00000000  Z=0.00000000
   X scale factor: 1.00000200
   Y scale factor: 1.00000200
   rotation angle: 0d0'0.0"
   Z scale factor: 1.00000200
         InsUnits: Feet
  Unit conversion: 0.99999800
  Scale uniformly: No
  Allow exploding: Yes

                  BLOCK REFERENCE  Layer: "Xref SMSR"
                            Space: Model space
                   Handle = 183f2
       Block Name: "Smsr"
                  External reference
                at point, X=0.00000000  Y=0.00000000  Z=0.00000000
   X scale factor: 1.00000000
   Y scale factor: 1.00000000
   rotation angle: 0d0'0.0"
   Z scale factor: 1.00000000
         InsUnits: Feet
  Unit conversion: 0.99999800
  Scale uniformly: No
  Allow exploding: Yes

Command:
LIST

Select objects: 1 found

Select objects:

                  BLOCK REFERENCE  Layer: "Xref Re SMSR"
                            Space: Model space
                   Handle = 348a5
       Block Name: "Smsr"
                  External reference
                at point, X=0.00000000  Y=0.00000000  Z=0.00000000
   X scale factor: 1.00000200
   Y scale factor: 1.00000200
   rotation angle: 0d0'0.0"
   Z scale factor: 1.00000200
         InsUnits: Feet
  Unit conversion: 0.99999800
  Scale uniformly: No
  Allow exploding: Yes

And using Lisp I can check a distance between the two insertion points to 0.00000000000000'

[AllenJessup]

---

@jbusBVFL wrote:

Is it possible the system variable INSBASE isn't set to 0,0,0 in all the drawings?

---

Good thought but both zero out to 8 places.

[Jeff_M · Accepted solution]

---

@AllenJessup wrote:

Nothing shows within the limits of the program.

                  BLOCK REFERENCE  Layer: "Xref SMSR"
                            Space: Model space

                at point, X=0.00000000  Y=0.00000000  Z=0.00000000
   X scale factor: 1.00000000
   Y scale factor: 1.00000000
  

                  BLOCK REFERENCE  Layer: "Xref Re SMSR"

   X scale factor: 1.00000200
   Y scale factor: 1.00000200

---

????

[AllenJessup]

Good catch Jeff! I should pay more attention. Or get some glasses.

Now I have to wonder. How did that happen?

[Jeff_M]

Well, it is the inverse of the Unit Conversion Factor listed for the block reference. That should be a clue.

[MMcCall402]

0.000002 is about 2 feet once you get out to the 600,000/800,000 coordinate range

[AllenJessup]

---

@Jeff_M wrote:
Well, it is the inverse of the Unit Conversion Factor listed for the block reference. That should be a clue.

---

0.999998 is the ratio of the US Survey Foot to the International foot.

But that would mean that AutoCAD (not Civil 3d) is somehow adjusting for International vs. US feet. AutoCAD won't see that the drawings are in the same coordinate system. The AutoCAD Units dialog box now gives the choice of Feet or US Survey Feet. Civil only handles that through the Unit and Zone tab in the Drawing Settings.

Both drawing are set to Feet in the AutoCAD Units. INSUNITS, INSUNITSDEFSOURCE and INSUNITSDEFTARGET are all set to 2 (Feet).

Is AutoCAD now scaling the insertions to somehow account for US Survey feet? If so. How can I stop that? This would account for a lot of problems I've had lately with drawing not quite matching after insertion.

[AllenJessup]

It obviously isn't happening all the time. If I attach the Xref again. It inserts at the correct scale. If I change the scale of the original instance of the Xref. It's in the right place. I was the one who attached the Xref to the Design Drawing. So what did I do wrong and why doesn't it happen when I attach it again.

I can accept that I missed a necessary change in procedure in the 2017 version. I don't want to deal with an intermittent that may jump up to bite at any time.

Another thing that confuses the issue is that is some circumstance both Xrefs list as one entity and in some cases as individual ones. That seems to be based on having highlighted it in the Xref Manager and what commands are used after deselecting it. So it's possible to select the scaled Xref and have the unscaled info in the Properties Dialog.

[AllenJessup]

I was working with Autodesk Support yesterday. They're as puzzled as I am. I duplicated the problem at least a half dozen time and then it stopped for no reason I could see. I had been working with copies of the drawing but when I tested it with the original drawing. I still couldn't duplicate it. This is a shot of one of the times I duplicated the problem.

So I know what happened but not why or why it suddenly stopped.

I checked the UNITS in both drawing and the Insertion Scale is set to Feet (Not US Survey Feet). INSUNITS, INSUNITSDEFSOURCE AND INSUNITSDEFTARGET are set to 2 (feet). AUNITS is set to 1 (Degrees/minutes/second), DIMAUNTS is set to 1, MEASUREINIT and MEASUREMENT are set to 0 (Imperial). The JP2 files are georeferenced in State Plane US Survey Feet. The only thing that specifies US Feet is the coordinate system set in both drawings. But the Xref command shouldn't react to that. Plus the State Plane Zone was the same in both drawings.

I guess this is just something to watch for in the future. I wish I had caught it when the Xref was inserted. I caused quite a bit of difficulty in having to adjust the propose on a nearly completed project.

[jmayo-EE]

This is the new acad unit of us survey feet in action. You may be learning our learning curve for working with the new units. 🙂

What if you set everything to US Survey feet. Acad and C3D?

[AllenJessup]

Yeah, John. I thought it might be the new unit. But if nothing it either drawing is set to US Feet, as far as AutoCAD is concerned. Where did it get the unit for block insertion. As posted I checked every setting that might affect attaching an Xref.

If both are set to US Feet the insertion would be correct. But it should have been correct with neither of the Units set to US Feet.

[jmayo-EE]

We keep our files unitless and the scale factor is correct also.

[AllenJessup]

That might be a good idea. I think the reason we have units set to feet in our imperial drawing is that the _AutoCAD Civil 3D (Imperial) NCS.dwt I started our template with has it set. Strangely I checked the _AutoCAD Civil 3D (Metric) NCS.dwt and it has units set to Feet as well.

[suvas]

Just exactly what I was looking for. Couldn't figure out why my xref has been off N-S by 590 feet. When I checked INSBASE, it was at 0,-590,0. I don't know when that happened. Thank you very much.