topic Re: RECAP RCS or RCP to C3D in Civil 3D Forum

RECAP RCS or RCP to C3D

apweng — Fri, 16 May 2025 17:48:20 GMT

Hello,

I am not fully understanding the difference between RECAP export RCP and RCS files? Specifically, does it matter which format I use to export to Civil 3D?

Thanks,

Andrew

Re: RECAP RCS or RCP to C3D

Pointdump — Fri, 16 May 2025 18:53:50 GMT

Hi Andrew,
Here's my understanding:
The RCP(P=Project) file is a pointer to a "Support" folder that contains, among other things, an RCS file.
The RCS file is an everything-all-in-one file.
Neither one is "better" than the other, and both are perfectly usable in C3D.
Dave

Re: RECAP RCS or RCP to C3D

apweng — Fri, 16 May 2025 22:31:28 GMT

That's fantastic thanks Dave!

Andrew

Re: RECAP RCS or RCP to C3D

apweng — Wed, 21 May 2025 17:22:35 GMT

Hi again Dave thanks for the response - very helpful!

We're trying to figure out best workflow for decimation - basically RECAP or C3D simplify surface. The latter seems to be the best option as it appears to provide better control for decimation (for example removing 90% of points such that maximum elevation difference is 0.1').

We're not sure how decimation works in RECAP. For RCS export are the following options...

Decimate ground points to 90% (leaves 10% in ground and moves 90% to model key) - and export ground points to RCS
Decimate ground points to 10% (leaves 90% in ground and moves 10% to model key) - and export model key points to RCS

When importing RCS to C3D using these options, the number of surface points is not the same, but very close.

Re: RECAP RCS or RCP to C3D

Pointdump — Wed, 21 May 2025 19:40:20 GMT

Andrew,
Decimation in ReCap seems insufficient to me, but I haven't tried it lately, so maybe they've improved it.
Simplify Surface is what most folks use. Works very well. BUT...if the dreaded MMS has already been created, then you might have a hosed drawing. My favorite method is number 3, "Distance Between Points". As you're creating a surface from the ReCap file, keep "Total number of points selected" to under 2 million.
Dave

Re: RECAP RCS or RCP to C3D

neilyj666 — Thu, 22 May 2025 09:27:26 GMT

I'd agree with @Pointdump that you need to avoid MMS files at all costs.

I'd also add that in Civil 3D 2026, it is possible to data shortcut a partial surface which may improve performance and reduce drawing size -I'm not using 2026 day to day yet so haven't got any more information regarding this feature but looks like it could be very useful.

Re: RECAP RCS or RCP to C3D

ChicagoLooper — Thu, 22 May 2025 13:50:01 GMT

@apweng

Decimation in RECAP is controlled in Advanced Scan Settings. The Advanced Settings are established before importing your file. Not after.

1. First setup your file and folder.

2. Next, click the Advanced icon. Use the slider to set your decimation, then click IMPORT (the import button not shown, it's in lower right).

Re: RECAP RCS or RCP to C3D

Pointdump — Sun, 25 May 2025 07:19:36 GMT

Andrew,
Playing with different workflows to decimate points in a point cloud containing 3,057,627 Pts:

1. Using ReCap's upfront Decimation Grid maxed out to 100mm only decimates to 2,173,726 pts. You still need to filter Ground(2) pts before exporting the RCP file.
2. In C3D, using "Distance Between" option set to 5ft produces a surface with 32,743 pts. Fiddly, but do-able, and gives you a good granular-level decimation.
3. Using ReCap's Intelligent Decimation set to 10,000 points produces a C3D surface with 9988 pts. Nice thing is you can pull those points out of only Ground(2) classification points.

Dave

Re: RECAP RCS or RCP to C3D

neilyj666 — Mon, 26 May 2025 09:03:33 GMT

The max decimation of 100mm is too small in my opinion for ground models probably as Recap seems to be promoting itself for building scans etc where I can understand 100mm being the maximum

Re: RECAP RCS or RCP to C3D

Pointdump — Mon, 26 May 2025 10:15:03 GMT

Neil,
"The max decimation of 100mm is too small in my opinion for ground models..."
I agree. Entirely inadequate.
Dave

Re: RECAP RCS or RCP to C3D

apweng — Mon, 26 May 2025 15:08:15 GMT

Thanks for all the responses.

Recap PRO has 2024 has decimation tool...

This works reasonably well but we are doing our decimation on the C3D surface as we have more control there over which points are removed. We're using just the Ground classification points for export to RCP/RCS for C3D consumption.

Andrew