Support additional segmentation models/parameters (e.g. NMS conf/iou thresholds)

[abrichr]

Segmenting images with many distinct objects results in many objects being missed, e.g.:

(Notice not all cells are marked.)

In OpenAdaptAI/OpenAdapt#679 we have good results using Ultralytics FastSAM for segmentation with very small values for non maximum suppression conf and iou:

    # threshold below which boxes will be filtered out
    conf: float = 0,
    # discards all overlapping boxes with IoU > iou_threshold
    iou: float = .05,

Incorporating FastSAM with parameterizable NMS would greatly increase the utility of SoM for tasks requiring high sensitivity and with many different objects.

Alternative suggestions for increasing the sensitivity with the current segmentation models would be greatly appreciated! 🙏

[abrichr]

We were able to get this working offline with FastSAM by just ripping out visualizer.py.