Improvements to simplify 3d polygons

[Steve Riddle]

Normally I write in to the troubleshooting section with complaints abouts issues and thought it was time I gave some positive feedback.  It was with some trepidation that I went to use the simplify 3d polygon tool on a complex 200Ha site model to make it useable, I had not much success with this process in the past and was pleasantly surprised when it worked perfectly! I was able to simplify the model to a state where it would refresh in seconds rather than minutes. This tool is a vast improvement on previous versions and a credit to the team that made it happen. 

[jeff prince]

I have to agree, this is a nice tool and I appreciate it.

[Shane W]

Hi @jeff prince I was wondering if you could explain what the difference is between simplify poly by "Maximum Deviation" vs "Minimum Distance" is? I've read the help description over and over but I'm still not completely sure what it's doing. 

So far minimum distance makes sense - I might for example want vertices no more than 1m apart.. but what about maximum deviation? When we're talking about a contour line, is going to move where the line is located? I have sites that are 50-150Ha but even on a small sub section of that, I want to ensure that where those lines are placed isn't deviating too much (or at all).. 

I've used Min distance before but (particularly with drone surveying) it results in loads of overlapping lines that takes hours to sort out, so I'm trying to find a more elegant way to speed up the workflow.

 

Edited May 9, 2022 by Shane W

[Pat Stanford]

Maximum Deviation works by removing vertices that are not required to keep the simplified poly with the specified deviation of the original.  

 

One example would be a gently sloped curve.  If the original had 40 vertices and you said the max deviation could be 6" from the original, it might replace those 40 vertices with 4 straight sections that simulate the original.  If this was over 50' it would be a good simulation.  If this was over 5' it might not be close enough.

 

Minimum Distance works the other way. It says that there can not be vertices spaced closer than the minimum distance specified.  So it you have a poly with an length of 100' and you specified a Minimum Distance of 5' it would give you at max 20 vertices and delete all of the others.

 

Minimum Distance with a long Minimum Distance will give you a small number of vertices, but it may not follow the original poly very closely.

Maximum Deviation will let you set a small allowable offset from the original poly shape, but at the cost of probably keeping more vertices than you need.

 

HTH

[Shane W]

Thanks.

 

So (in theory) on a large site, if I was to start with Maximum Deviation (with only say 15cm) I would get the lines roughly where they were, and then I could go and do minimum distance to reduce the cont further..  

The problem with using aerial drone surveying is that the trees trick the resulting contours so I'm trying to find ways to reduce the amount of time spent manually editing contours. 

 

[Pat Stanford]

Yes, something like that should get you something close but with a lot fewer poly segments/vertices.

 

I would try it in a test file first and keep a copy of the original data so you can compare how they work and decide if they are close enough for your purposes.

[Shane W]

Thanks @Pat Stanford

Unfortunately neither method really does the trick.

As you can see it ends up crossing the contours over, so I have to go in and manually edit them... over several hectares this is very laborious and time consuming!  

 

This feels like a major limitation of Vectorworks for working with landscapes. It's fine for dealing with small gardens, but the way the software is written it is not set up to handle more than a few hundred vertices on 2D shapes which is very limiting (and it taxes the CPU while barely using the RAM or GPU of the computer to handle rendering or display). The site modelling, editing and rendering (along with pathways) is painful to use for my purposes - which is disappointing for such pricey software. I like the tools, and on paper it seems great but in reality it just doesn't really seem to work very well for designing the larger landscapes, dams, roads etc that I need it for. If I was designing buildings and doing patios and flower beds it would be fine I guess... but it's very frustrating how many hours of my precious time I waste having to 'work around' VW all the time. It could, it has the tools, but the implementation is just heavily geared to architects. 

 

I'd love to be able to just take in the contours 'as is' and just do some 3D smoothing to level out some areas that are falsely rough from trees being included as terrain, or even have some way of averaging those lines without them overlapping ..but alas..  

 

 

[Pat Stanford]

I will leave it to others to offer more advice on Landscape/GIS workflows.  Sorry it is not working well for you.