Projecting Points and Circles in Polyworks

Published by CMMXYZ on September 15, 2023


The video demonstrates how to project surface points and circle features onto scanned data in PolyWorks. This method is commonly employed when measuring or calibrating a check fixture using laser-scanned data.

Welcome to a new video on tech tips from CMMXYZ. In today's tech tips video, let's see how a feature or a point can be projected on the scan data in PolyWorks. I have a CAD part aligned to the scan data of a check fixture. Here, I'm testing the accuracy of the check fixture using a CAD model on which the check fixture was designed after. Let's start with checking the gap. Here, the nominal gap between the CAD and the fixture is 6 millimeters.

To check the gap, take a comparison point on the CAD model, go to Surface Comparison Point option, and check Extract Measured Component, and anchor a point on the CAD model in the area where we are checking the gap. Close the Surface Comparison Point dialogue, and then in Preview, right-click on the Surface Comparison Point. Go to Edit and select Invert Orientation. By doing this, we are inverting the vector of the comparison point. A message shows up warning you that the comparison point is linked to a reference object. By inverting the orientation, this link will be broken. However, the nominal will be taken from the CAD. Say Yes to continue.

Next, again, right-click on the Surface Comparison Point and select Properties. In the Properties, go to Measurement tab and change the method to Extract. In Extract method, select Comparison Point Distance, and check on Offset. Enter the nominal value of the gap from the nominal surface of the CAD model and apply the changes. Here, I'll enter -6 as I've inverted the vector, and apply the changes and close.

Then, to extract the comparison point, right-click on the Comparison Point in Preview and select Extract Measured. The measured value that you see is the deviation of the surface, which is supposed to be at a distance of 6 millimeters from the CAD. After projecting a surface point, next, let's project a circle feature on a scan data in PolyWorks. First, go to the Feature toolbar to create a circle feature on the CAD. In Method, select Pick on CAD Model and create a circle on the CAD.

Next, we have to invert the vector of the circle. This is done to extract the measured value from the check fixture. In Preview, right-click on the Circle feature, go to Edit, and select Invert Orientation. Selecting it would show a dialogue box with two options. Checking on Invert Axis would invert the vector of the feature, and checking on Invert In-space Orientation would change the feature type from internal feature to an external feature or vice versa. Check on Invert Axis Orientation and click on OK. This will change the axis orientation of the created circle.

Last step is to project circle to the scan data. To project the circle, right-click on the Circle feature, go to Edit, and select Translate Along Axis. Selecting Translate Along Axis would open a dialogue box, which allows you to enter the distance for translation of the circle feature. Enter a distance to translate, here, I'll enter a pre-measured distance of -33 millimeters and click on Apply. Clicking on Apply would translate the circle on the scan data in the direction of the vector. After the circle is translated, close the dialogue box, and in Preview, we can right-click on the Circle feature and then select Extract Measure to get the measured size and location of the pole in the check fixture by taking nominals from the CAD.

This was a video on projecting surface points and circle features on a scan data in PolyWorks. Thank you for watching the video.

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