Ailgning Cameras within the same rig giving a calibrated xml file

[Adsh]

Hi I am trying to do a batch processing on my own camera rig. So I first calibrate my camera sets by placing a texture cube with scalebar inside the rig, and run metashape UI, pick the markers and set up the coordinate. Then I export the calibrated camera xml file for referencing of the batch captures. I expect the template camera xml file can help me keep the true scale as well as the coodinate of my rig while processing other captures without a scalebar.

Then basically I am using the following python code:
chunk.addPhotos(xx)
chunk.importCameras([the template xml])
chunk.matchPhotos()
chunk.alignCameras()
Chunk.buildDepthMaps()
chunk.buildDenseCloud()
chunk.buildModel()

And I am getting a mesh of poor quality, and some of the time getting only few patches/strips. Looks like the alignment of camera failed. I output the camera xml after the chunk.alignCameras() and see there is no difference between it and the template xml.

Does anybody know which step I goes wrong? Or what is the correct way to achieve the goal of using a template to scale the captures without scalebar in a same rig? Thanks a lot.