Wednesday, 7 August 2013

Recap to Civil 3D

This post outlines a workflow to import a point cloud into Recap, edit it, export a section of it to Civil 3D and then create a surface from it in Civil 3D.

I would imagine this is a work in progress given the series of steps that you have to go through to import a section of the point cloud into Civil 3D, see what you think.

First of all import your raw point files into Recap, click on New Project:
Browse to your raw files and click next. You can edit the settings here to remove noise, or specify the minimum space that any one point can occupy (decimation grid).
After importing the raw files, if you browse in windows explorer to the folder where the raw files were you will notice that there is now an .rcs file. This is the Recap indexed point cloud file. When you want to import the point cloud into any of the other Autodesk software packages it is this rcs file that you import.
Once you have your point cloud in Recap the first thing that you may notice is that the point cloud doesn't appear to be as dense or as detailed as you would expect, or that there appears to be sections (strips) of points missing.
This is purely a visual thing, all your points are there! There are a few changes that you can make to improve the appearance....
The points are lit from either one or two sides by default. Turning this lighting off improves appearance.
Secondly you may need to adjust the point cloud origin so that it is on or near the points themselves or the area of interest.
Follow the prompts on the screen. For this example I chose a point on the road surface and pressed the TAB key to flip the axis so that the 'Z' axis was in the correct direction.
You can also reduce the point size which will also impact appearance.
The result will be a much clearer looking point cloud:
The next thing we need to do is to clip out the portion of the point cloud we wish to import into Civil 3D. I am going to clip out a section of the road and then edit this to remove any points that I do not need, such as the trees you see on the left in the screen shot above.

Use the window or fence select tool to highlight the area you wish to keep...

Then click on Clip Inside to hide these points. Use the select tool again to select the remaining points...
...and click on delete. Click on Unclip All to restore the points of interest. Next use the fence selection to select the points comprising the road and verge...
...repeat the clip inside, delete, unclip procedure until you are left with only the points you want.
Once you have tidied up your section of interest it is important to point out here that the edits you are making are not saved back to the rcs file. The only way I have found of being able to effectively save these changes to an rcs file is to export the points to a raw point file format first and then reimport them back into Recap so that it creates a new rcs file. To do this click on export first...
Select a file format to export to and wait...
Next start a new Recap project and import the file you just exported. This then creates an rcs file for just the edited section of points, which you can then import into C3D...

Civil 3D:
In Civil 3D then, go to the Insert tab of the ribbon, click Attach and browse to your edited rcs file...
Your point cloud will appear in C3D..
In order to create a surface from this in Civil 3D you will need to give the Recap point cloud Civil 3D properties.. click on the point cloud and on the ribbon click Add Civil 3D Properties...
Once you have done this, click on the point cloud again and select Add Points to Surface on the ribbon. Before you do this however make sure that your viewport visual style is set to 2D Wireframe or else it will not add the points. See screen grab below, just however your mouse around this area of the screen and you will be able to change the style.
You can also change the view style from the View tab of the ribbon.
Once the surface is created you may find that it is far too dense for your requirements. For example I have a point every 5mm in my example which is complete overkill for what I need. You can simplify your surface to remove points. Select your surface and choose Simplify Surface.
Select Point Removal as the simplification method
On the last tab you specify the max change in level between adjacent points, it removes points based on these settings. An in depth explanation of how this works can be found in the help menu.
One thing to note here is that when you click finish it runs the simplification. So if you click Apply and then finish it will run the simplification twice and possibly remove more points than you had planned.
All of the above amounts to a pretty long winded workflow to create a surface from a point cloud in Civil 3D. It works well but there is room for improvement, for example when you trim the point cloud in Recap you should be able to save this out as an edited rcs file without the extra export/reimport steps. 

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