Need better tooling to resolve "floating islands"

I wrote about some of the challenges I have with the slicer and fine-tuning supports in Preform:

Since then, the situation has gotten even worse as switching from “Normal” to" Support Editing" mode in recent versions of Preform causes the model to jump upward along the Z axis (simply put, you lose your place).

Does anyone else find Preform makes it unreasonably difficult to place supports where they need to be to fix your “floating islands”? Autogen does a decent job but does not catch all of them. I can provide sample STL’s.

There is a slicer in the support editing mode but it seems to work in the opposite direction from what I need (and I’m guessing it’s intended for work on internal cavities, not what I’m doing). If there were simply an option to invert the support editing slicer direction I think that would solve my issue.

Let me know if this is unclear; I can explain/elaborate.

We’re always working to improve unsupported feature detection and I’ve made sure our software team is aware of the ‘jump’ you’re seeing when entering support edit mode. A few other users have noticed that it can make precisely placing support structures a bit difficult.

We’ve found that the inverted slicer makes point placement a bit easier. Islands should be more apparent when slicing up through a model and placing points should be a bit more straightforward. Has this not been the case for you?

Hi Frew,

Grateful for you taking a look at this for me, and glad to hear you guys are on top of the “jump” issue.

I like to manually verify printability by stepping through the layers of my print and watching it “grow”. When I’m in the normal slicer (i.e. not editing supports) that’s really easy to do. I look “down” on my print (i.e. The build platform is beneath me, surface side up, and I’m looking down onto it). The slicer handily distinguishes between support structure (orange) and model slices (blue). I can see the previous layers, which is important. When I increment, it’s easy to comprehend the transition between the two layers. Since the software shows what’s already printed underneath the current layer, it’s obvious to gauge how supported it is, and trouble spots like large overhangs and islands really stick out.

In support editing mode, I need to switch to a “bottom up” view of the print in order to do anything useful. (i.e. I’m now on the “lever” side of the build platform, looking up through it, through it’s surface, and toward the future layers of my print).
While this does make it easier to place a support, I find it much more difficult to spot islands and overhangs when walking through the layers. Since the previous layers are no longer shown, I don’t have the same sense of how well supported the current layer is. I have to flip back and forth to see the transition - while that’s very useful to do when working on an individual support to coax it into the perfect location, it’s makes for an impossibly slow workflow when trying to skim through the build. I find it harder to spot islands and overhangs unless I already knew/suspected the current layer has one.

I think it boils down to the difference between watching your model “grow”, vs. watching it get sanded away. I agree the slicer view is easier for placing supports, but by the time I’ve spotted an island in the main view I already know exactly where I want to put the support. I wish I could just click and be done with it, without having to suffer a disorienting camera flip to the underside of my model. e.g. It would be great if the support simply got placed on the nearest surface of my model underneath where I clicked. By definition, an island is the first thing to present, so I already know the slice I’m attaching a support to is on the outer surface of my model and there’s no need to go hunting on the underside for a place to put it.

Other ways to solve would be:

  • Have an option to toggle between normal and inverted slicers in the support editing view
  • In the existing slicer, allow me to click anywhere in my main view to “mark” the spot (e.g. with a little X) to make it easier to locate it after switching to support editing mode and undergoing the camera flip. A hotkey to center on the X would be a nice touch.

That’s my two cents. Hopefully I’ve made the pain point clear; if not I’m happy to demonstrate at the user conference next week. Let me know if you think I’m “doing it wrong” and this is a training issue.

I agree you guys are always making great enhancements to the software, hopefully this feedback can lead to some more of them!

Since a picture is worth 1000 words:

Normal slicer:

Support editing slicer:

That makes perfect sense and I agree that the change in camera between object and edit mode is a bit disorienting and can slow down workflows a bit. We’re looking into getting that jump corrected.

The toggle between normal and inverted slicers is interesting as well. The inverted slicer is necessary for identifying surfaces inside of cavities but a toggle between the normal and inverted slicer might make identification of islands easier. I’ll forward your toggle idea to our software team and checkup on the status of the jump.

I would like to have the layer(slice) numbers displayed in the support edit mode as well. Although the issue with losing the place can’t be overcome by displaying layer numbers, it greatly helps me in narrowing down the slice I am interested in. I use a bit of hack to do this currently. I note down the layer number that has an island in Normal mode and then switch to support edit mode and I use the Shift Pg Up (this increments by 10 layers) and finally use the Pg Up to increment by one layer at a time.


It would be good to be able to adjust the slider by entering the layer number into the display box.


Just wanted to voice my support for @billb and @pr19939’s ideas of being able to see the layer number in support edit mode as well as being able to type the number and jump directly to it.

This would be a fairly unintrusive thing UI wise and would beneficiate a majority of users IMHO.

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This would be really helpful to me as well.
I would also suggest adding a transparent mode toggle in edit mode. If you had the option to show a ghost image of the rest of the model below the support areas it could make it easier to identify unsupported areas.

I also believe this floating island behavior becomes more prominent when you reduce the point size of supports. It also seems that on symmetric models the algorithm will catch an island on one side of a model but not the other.

I would previously hollow models to save material but have mostly stopped because if I miss a floating island on a large part it will blow up a very long print. The automatic supports do not catch them and on large or complex models I can miss them too.

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Hey @Frew, did that “jump” issue get fixed? If so please pass along my thanks to your team. Did they have any thoughts about a slicer direction toggle or other approach to more efficiently identify and support floating islands?

Models do still jump a bit when entering support edit mode but I’ve followed up with our software team and we are looking into a fix for an upcoming PreForm release. I’ll keep you updated! We’re working on features to improve island and unsupported feature detection holistically and a slicer direction toggle is something we’re actively considering.

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