In order to scale the model without the Professional Edition of Metashape, we need to use a 3D software to scale it. I am using Cinema4D here, as this is the same software we use for our 3D modelling class. Other 3D software will be fine too, but the process might differ a bit.

If you open up the OBJ file with Cinema4D, an import dialogue appears. We basically can leave everything as it is, but make sure that you have chosen Import .MTL File in the Material option. Hit OK. The object should appear, although not oriented or scaled. The first thing we do, is to go into our Material Manager at the bottom and select Edit and Delete unused materials. The second step should be the orientation. We want the object to be levelled in the XZ-plane and directed to the Z-direction.

We first open up the Axis Centre Tool by pressing SHIFT+C and enter “Axis Centre…” to select the tool. A new small window appears in which we scale the Y-value down to -100%. Hit Execute. This places the objects axis in the centre bottom of the object. To centre the object correctly, we kind of need to adjust the direction of the objects axis to the object itself. For this we need to turn on Enable Axis from the left menu. Now, in the Side and Front view (F3 and F4), we rotate the object axis to align the Y-axis (green) with the top of the object. We then open up the command line again (Shift+C) and enter “PSR” to select the command Reset PSR. This way the object jumps into the right direction. We then alter between correcting the axis, resetting the axis centre and resetting the PSR. We do this for the side view, then the front view, then the side view again, until we are happy. Lastly, we orient the top view (F2) so, that the front of the object looks into the Z-axis direction (blue).

As we have oriented the object properly, we can now start the scaling process. To know how much to scale the object, we first need to know how long a know value is at the moment. Luckily, we did put some form of measurement into our model and can measure that. To measure within Cinema 4D, we use the Measure & Construction tool, which we again find through the command line (SHIFT+C). We change into our top view (F2) and click somewhere on our measurement. We then click & drag the second point of the red line to another point on our measurement, so we do know how long the distance should be. In the screenshot, I chose the 10cm and the 20cm mark of my ruler, so I know the distance should be 10cm. As I can read from the Measure & Construction tool, it is only 0.831cm though. So we need to get the model bigger. To calculate how big, we simply divide the 10cm that it should be with the 0.831cm that it is at the moment. The result is a factor of 12.034.

With the model selected, we can scale it to that factor by looking at our Coordinate Manager right beside the Material Manager. In the central column, we see the Size of the object. At the bottom, we can change the dropdown to Scale. First: Make sure that you are not in the Enable Axis mode. Simply deselect it on the left menu, so that it does not appear blue anymore. Then enter your calculated scaling factor in all three fields of the central column in the Coordinate Manager and hit Apply. You can zoom out and check the measurements. It usually fits quiet well. You can delete the red measurement arrow by selecting the Measure & Construction tool again through the command line (SHIFT+C) and hitting the Delete Measure button. Your model is now scaled!

  • sfm/chapter08.txt
  • Last modified: 2020/11/22 10:47
  • by shageneuer