How to georeference, scale and rotate a DXF file using AutoCAD - PIX4Dcloud

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When importing a DXF file into a PIX4Dcloud project, it is possible to encounter issues that prevent the correct file display in the 2D viewer. This article provides solutions to the most common problems encountered after importing a DXF file as a Design Overlay.

DXF file is not displayed in the 2D viewer

The DXF file has to be in the same coordinate system as the project created in PIX4Dcloud. If the coordinates are different, the file is not visible at the expected location, but it shows away from the project area.

This can happen when a DXF file is in a local coordinate system that is different from the project coordinate system. For this reason, it is necessary to georeference the DXF file before importing it into the project.

Solution

  1. Open the project on PIX4Dcloud and identify a point (Point 1) in the orthomosaic that is easy to find in the DXF file.
  2. Save the (x,y) coordinates of Point 1 in a text file.
  3. Open the drawing in AutoCAD.
  4. In the console, type Move.
  5. Select all objects of the DXF and hit Enter.
  6. Specify a Base Point (Point 1 that was identified in PIX4Dcloud) and hit Enter.
  7. In the console, write the coordinates of Point 1 (x,y) stored in the text file and hit Enter.
    All the objects in the DXF file are now written in the project coordinate system.
  8. Save the changes by clicking the save icon save_icon.png on the Menu bar.
    • File name: Type the desired name.
    • File of types: Select AutoCAD 2018 DXF (*.dxf).
  9. Import the new file into PIX4Dcloud.

For more information, Import a design file in DXF format into PIX4Dcloud.

DXF shifted with respect to the orthomosaic in the 2D viewer

It is possible that, when importing the DXF file as a Desing Overlay in PIX4Dcloud, it appears off with respect to the orthomosaic in the 2D viewer. The most common causes are the following.

Incorrect bounding box

There are elements outside the project area that make the bounding box of the data very large.

Solution

  1. Open the project on PIX4Dcloud and identify a point (Point 1) in the orthomosaic that is easy to find in the DXF file.
  2. Save the (x,y) coordinates of Point 1 in a text file.
  3. Open the drawing in AutoCAD.
  4. Select only the elements that must be seen on PIX4Dcloud and copy them by clicking Copy Clip on the Clipboard bar.
  5. Create a new CAD template and paste the selected objects of the DXF.
  6. In the new template, follow these steps:
    • In the console, type Move.
    • Select all the objects in the drawing and hit Enter.
    • In the console, write the coordinates of Point 1 (x,y) stored in the text file and hit Enter.
  7. Save the changes by clicking the save icon save_icon.png on the Menu bar.
    • File name: Type the desired name.
    • File of types: Select AutoCAD 2018 DXF (*.dxf).
  8. Import the new DXF file into PIX4Dcloud.

Objects unsupported by the 2D viewer

The DXF file contains objects that the PIX4Dcloud viewer does not support.

Solution

  1. Open the drawing in AutoCAD.
  2. Select all the objects in the drawing.
  3. In the console, type EXPLODE.
  4. Save the file in the DXF format.
  5. Import the DXF file on PIX4Dcloud.

DXF with incorrect scale

It is possible that, when comparing the distance between two georeferenced points, the distance is not correct, and in this case, it is necessary to rescale the drawing.

Open the DXF file in AutoCAD and follow the instructions on how to scale a drawing in AutoCAD: How to resize or rescale an AutoCAD drawing.

DXF with incorrect rotation

It is possible that, when comparing the position of some points selected as a reference, the drawing is not rotated in the correct position.

Open the DXF file in AutoCAD and follow the instructions on how to rotate the drawing in AutoCAD: ROTATE (command).

Two other possible workarounds are described in the following link, Importing DXF - distortion/rotation issue.

 
Information: Sometimes, there might a combination of the errors above, e.g. a DXF file has a wrong scale and a wrong rotation at the same time.
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