Thank you, everything is working as expected now. Not sure why the scale wasn’t working before but for my future reference, these are the steps I took to get correct scale and orientation for modelling (I prefer to model at real-world scale)...
- Add a camera to the scene
- Go Tags > Tracker Tags > Camera Calibrator
- In the Calibrator Tag, switch to the Image Tab
- Click the … button and choose the image to calibrate
- Untick ‘Keep in foreground’ so we can see the grid
- Go to Render Settings and set the width/height to the same pixel dimensions of the image
- Go back to the Camera Calibrator tag and click the Calibrate tab
- Click ‘Add Line’ and move it onto an obvious left to right line in the image
- Shift-click the line until it turns red
- Add more lines (1 or 2) to the same left to right orientation, and shift-click to turn them red
- As more lines are added, the Calibration Status boxes go from red, to orange to green
- Once green for X Vanishing point and another line
- Move it onto an obvious right to left line in the image
- Shift-click until it turns blue
- Add as many Red (X) Blue (Z) lines until all boxes except ‘Camera Position’ turns green
- Click ‘Add Line’ and move it onto a vertical line where you can see the full height of the line in the image where you know the real-world length
- Click ‘Add point’ and position onto the bottom end of the vertical line
- Now click the line and check ‘Known length Y’ and enter the height
- All boxes should now be green
- Click the ‘Create Background Object’ button
- Lock the camera by selecting it, right click and go Tags > Rigging Tags > Protection
