A little while back, I invested in a hobbyist CNC machine and have been learning a bit of Fusion 360 for design and CAM. Well of course the YouTube algorithm picked up on this and inundated me with videos from people with far greater knowledge, experience, and hardware. None the less, I saddled up and thought I might give a project that interested me a try. Enter, topographical maps.
After watching about 20 different methods of getting height map data into usable three dimensional models, I settled on the Blender 'plane diffusion height map method' for that beginning phase of the workflow. This left me with beautifully detailed, truly astonishing models by my standard of literally having downloaded Blender only hours before. I exported those thick .stl files, confident that Fusion would throw me a curve ball or two, but nothing I couldn't handle. It was around this time I learned about triangles and Fusion's fairly strict under 10,000 faces policy.
Fast forward a year, hours of videos, forums, trial and error, even a brand my first child, and I still cannot get Fusion to give me a T-spline for CAM that I am satisfied with. I've done other projects to keep me fulfilled but I keep returning to this. Recently, I've used @TrippyLighting's method through InstantMesh to provide pure quad models and they either come out looking like ice cream at various stages in a microwave or Fusion out right folds it's arms and locks up during some point. Even when I get to the incredibly close moment of the convert mesh to t-spline stage, I am met with daunting "repair" requirement; a task by the way that is by far the most consistent and fastest way to freeze Fusion for literally hours. In the few times I've gotten a model small enough, and consequently one with too little detail for me to use - but I pressed on to see if I could at least get something to work, Fusion kindly reminds you that meshes are not in fact t-splines and therefor the "repair" option in utilities is useless because the mesh object before you is unselectable and therefore unrepairable. Either that or I'm missing something and it's a task that takes about 20 minutes to attempt each time.
At some point I went back to Blender, as a reminder, a program I know even less about. I tried different methods for generating topography including a GIS plugin that apparently pulls in height maps and terrain like magic. As a small aside, I even had to edit some... python? through... notepad++? to increase the size of the height map attainable by this plugin. I include that last bit to punctuate the point, if I hadn't made it clear by now, that I have no clue what I am doing. And alas, no luck there either. The models either lose their stark detail and rigid terrain features making everything soft rolling hills, or the model complexity is just over the threshold of what Fusion is willing to entertain and again crashes or otherwise fails at some point.
I understand that my problem is equal parts a lack of knowledge and too high of expectations for a project but I thought I'd reach out to this community of experts to see if their is a better workflow for this sort of project by now before I spin my wheels any further. The models I am working with have face counts well over 50,000. I'm fine with trying to reduce the face count but I have so much information in such a large grab of terrain data that I can't seem to make a model with a happy medium between detailed and realistically usable. I don't want to CNC a coaster sized 64x64 quarter inch high map. I want to carve a decent sized piece, maybe like a 12" radius to start of say... Hawaii or some other little coastal paradise. Is that too much to ask? Do I need to pony up $500 for something like MeshCam? Do I need to enroll in night classes for Fusion? Do I need a coffee?
The answers to these questions may never be known but I had to reach out. The Autodesk community has always been helpful and enlightening and I greatly appreciate anyone that took the time to make it though to the end of this post.
TL;DR: Fusion hates Mesh, my STL models are too large, the other workarounds either crash or lose too much detail.
As a token of my appreciation, look at this completely unusable pipe dream of model of Hawaii that despite being simple to make in Blender, I am quite fond of it nonetheless:
