Follow these steps to calibrate your GigE camera.
- Place a calibration grid on the machine table.
- Take a raw photo of the calibration grid in IGEMS CAD/CAM.
- Make a calibration of the grid.
Place a calibration grid on the machine table
To calibrate a camera, you need to place a calibration grid on the machine table. A denser grid will make for a better calibration. We're making our calibration at the IGEMS Test lab from a grid spaced 200*250mm (8*10 inches), and the camera is placed roughly 2.5m away from the center of the grid. Make sure the grid material is thin as it will give a better calibration.
L stop
Place the grid resting towards your L stop, highlighted in yellow above. If you don't have an L stop, we recommend you make one where the inside corner represents your machine’s zero point. You can easily make one by bolting a sheet to your table and cutting the shape by following the outer limits of your machine's X and Y movement.
Take a raw photo of the calibration grid in IGEMS CAD/CAM
To prepare IGEMS CAD/CAM for the calibration of the camera, please follow these steps.
- Open the Camera calibration command found on the Tools tab in IGEMS CAD/CAM.
- Select your camera from the drop down menu.
If you don't see you camera in the menu, please follow this guide. - Insert a raw, unmodified image from your camera into the current IGEMS CAD/CAM drawing.
- Start the calibration.
Make a calibration of the grid
The first step when calibrating a camera is to tell IGEMS CAD/CAM what your grid looks like and the placement of your camera relative to the origo of the calibrated image (often the machine zero point). For the best calibration, measure from the camera sensor to the first point of the calibration.
- The number of points in x and y. The number of points is same as the number of squares+1, so if you have a grid of 6x4 squares, the number of points in x is 7, and the number of points in y is 5.
- The size of the individual calibration sheet squares in X and Y.
- The thickness of the calibration sheet.
- Camera placement relative to the machine zero point (First point in the machine image below).
When these parameters are filled in correctly, press the "Pick points…” button to enter the geometrical tuning of the calibration. This step begins with specifying the outer limits of the calibration area. This is done by picking the four corner points of the full calibration area, starting with x-min, y-min, and going in counterclockwise order.
When the outer limits are specified, IGEMS will make a rough guess of the grid squares visualized as pink lines on the image above. This rough guess has to be fine-tuned by the operator to be coincident with the corners of the square corners in the calibration sheet in the raw snapshot. This can be done by either dragging the grips of the grid, or ctrl-click to place them directly. This step is the most critical to get good accuracy of the final image. When done, press Enter to confirm the calibration.
You are now ready to take a ‘real’ birds eye view of your machine table.
Edit your calibration
The ‘Edit calibration’ button in the camera manager will let you enter the geometrical tuning to modify the grid points. This is useful in case the camera has moved slightly, so you don’t have to start over with a new calibration.
Edit your camera brightness
If your image is too dark/black, you can modify the shutter time and gain of your camera by pressing the ‘Stream’ button in the camera manager (in case your camera supports those settings).
Edit the focus of your camera
The stream button is also useful to tune the mechanical focus and iris on the camera, as you will get a continuously updated camera picture.