Dam Construction Modelling

Hi SketchUp people

I’m attempting to create a 3D model of a proposed detention dam and have been struggling to import an existing ground surface, upon which to base my modelling. The surface in question has been created using Lidar data (pointcloud based on aerial survey data .dxf/.dwg). The surface is large (in data terms) as a result of this, and while I can get everything into my model, it’s understandably hard on the display and slows everything considerably.

What I’m looking for are suggestions around how I might remove some of the density from the surface. Can I, for instance, convert the .dxf/.dwg into another form of surface.

I realize that SketchUp might not be quite the right program for this scale of modelling, but I am limited to the tools I can get my hands on. I currently have access to programs for road design and survey, which are not really cut out for rendering etc.

Any help people could offer would be greatly appreciated.

Thanks in advance.

The imported .dxf/.dwg data comes into SketchUp as a group (when modeling space was not empty) and contains edges, no faces. The mesh needs to be skinned. It’s not quite clear what you have at the moment. But there are tools to simplify curves to more suitable segments.On the other hand this might not be what you ar looking for at all. Hard to tell.

There are techniques (with groups and layers) that let you reduce what SketchUp needs to handle on screen while modeling. Say just the most needed area data near the dam (as reference) and the dam itself that you are working on.

Can you tell us a bit more? What is large to you (area / file size)?

I might be able to help but not sure. You will need to reduce the point cloud data to make the model faces manageable for SketchUp. You might want to try a third party program like MeshLab which can reduce the overall number of faces. You can either start out with your Lidar data and bring into these programs or take the SketchUp model and do it. Might get different results but worth exploring.

one question: how many faces are you dealing with currently in SketchUp (Window → Model Info → Statistics (make sure Show Nested Components is checked).

I know working with a 3D surveyor that I make them ‘dumb’ down some of the data they have. They use programs like MeshLab to do it. There are some others. I can find out. But even for programs like Revit, 3DS Max and Civil 3D, the point cloud data sets are still to rich.

Another option (and this is what the 3D Surveyor does) is remodel the Dam from the data you have in SketchUp. In Essence, retrace the dam to reduce the overall face numbers. I have done this in the past for buildings I get from Revit. It can be tedious but with Extensions is possible.

Use the Lidar Model and an outline to ‘trace’.

Last, there are plugins that will reduce faces (need to find out which ones) but they are hard to get to work in SketchUp once the model face count reaches a specific point and if there are many faceted / curved surfaces).

Please let me know if this helps. I can get more info on this topic. It’s a tough nut to crack.

Daniel Tal

Just found out about this today: Polygon Cruncher
Works with SKP files as well as others.

It has a full featured trial period.
Go to: mootools.com download page
And in the picklist, hilite “3DBrowser for 3D Users + Polygon Cruncher

It is an external listing in the Trimble Extension Warehouse, but there are no reviews yet.

Try it out and please add a review for us?

Here is another SketchUp plugin that says it can
“Create simplified terrains over complex terrains”

It is subscription based, $7 / year (at this posting.)

Only 1 worthless review in the EW for this one. A proper review is needed.

Thanks and apologies for the delayed response.

I’m going to give this a try - will let you know how I go.

Thanks Dan. Yes, it worked perfectly and I posted feedback as requested. Problem solved.