Select Regions of Interest

Frequently, you will generate a 3D model that consists of more parts than you want to focus on. For example, if the CT Scan covers the whole chest, but you are only interested in a particular body tissue or organ. In order to narrow down to the parts that your after, you have two options: crop the model using the crop tools, or, use either of the buttons below which allow you to extract disconnected parts.

1. Extract Largest Connected Surface

Take a head scan for example. A generated model of the cranium may often contain the head rest/support used during the CT Scan. A simple click of this button (top right), will automatically detect the largest individual surface in the model, and extract it, deleting all other disconnected parts. The same function can be used in cases where the generated 3D model contains multiple body tissues, of which you are only interested in the largest tissue. So long as the part you’re interested in is disconnected from the rest, and is the largest single surface, this function is ideal.

2. Select Regions of Interest

We will use a CT Scan of feet as an example here. An analysis of the feet bone structure, would yield a generated 3D model as below. Here, if you’re interested in extracting both feet, you would use the Regions of Interest Button. The button activates a function, that detects all disconnected parts. Once done, you would simply need to select (left-click) on each part that you wish to keep. Conversely, if you accidentally select a part that you wish to de-select, simply right-click on that part. Any selection is adjusted to red. In the 2nd Image below, each of the two feet have been selected.

If any smaller parts turn out to be disconnected in the 3D Model, as for the toes on each foot still in yellow, simply continue to select each of the individual parts until all regions that you are interested in have been selected.

Finally, once you are satisfied; if using Windows or Linux, there will be a Keep and Cancel button included in the 3D window. Select the Keep button to extract your selections, or Cancel, to restore your original model. If using MacOS, in place of the Keep button, press Enter/Return on the keyboard to perform the extraction. In place of the Cancel button, press the Escape key.


Keep an eye on the progress bar as you use this function. Once it reaches 75%, disconnected regions are ready for selection as described above. Before that, depending on the complexity of your model, give the software a few moments to perform the necessary computations to isolate all disconnected parts for selection.