Import parcels with true curves from ESRI

[Chris_Baze]

I am trying to import parcels from https://honolulu-cchnl.opendata.arcgis.com/datasets/parcels-regulatory/explore

I was able to import the shapefile with segmented curves, but I need true curves. I understand that a shapefile cannot contain true curves, but the geodatabase can. Does anyone know of a way to import these parcels with true curves?

[TerryDotson]

It may be possible to restore the arcs in the resulting shapefile import by analyzing the segments.  We have worked on a Restore Arcs tool in the past.  If you could provide a link to the specific shapefile from the site you listed, we would download it and try the tool on the file and evaluate the need for any improvements and post the results for you to potentially use.

In a past life I taught Map3D classes, I thought there was also such a process in its Map Cleanup tools?

[Chris_Baze]

shapefile attached

[TerryDotson]

Thanks for the file.  At a glance it looks like it's in WGS84, so it needs to be projected to some state plane system for reasonable distances (feet or meters).  What is your target CS?

Command: CGEOCS

[Chris_Baze]

The City and County of Honolulu uses State Plane Hawaii Zone 3 (Oahu) Coordinate System and the NAD 83 Harn datum . 


We recommend the projection with NAD 83 Harn for several reasons.  It supports the use of survey grade GPS, it is more accurate than NAD 83 and has become the modern standard at the National Geodetic Survey.

Projection: State Plane Hawaii Zone 3 (Oahu) Coordinate System

Units: feet
Datum: NAD 83 Harn

ArcGIS Projection File Name: NAD_1983_HARN_StatePlane_Hawaii_3_FIPS_5103_Feet

Units: Feet

Spheroid: GRS 1980

[TerryDotson]

The closest named system in Civil3D I see would be ...

CGEOCS = "HARN/HI.HI-3Fa"

@Pointdump, opinion?

[TerryDotson]

The way the tool works is by finding a collection of close vertices along a figure (in these cases polylines).  It then takes logical clusters, determines the end points and uses them and a halfway point to define a CircularArc and substitutes that for the collection of close points.  To determine the points, it uses a maximum distance, in this drawing it's around 3.6 or so.  This is a picture of one processed parcel, the cyan content is temporary construction geometry just to show what it did.

On this example it replaces three clusters with 3 arcs on the polyline.  Once you determine a named Civil3D coordinate system as returned by the CGEOCS variable, I will process the entire file (in one pass) and post it.  At that point I would recommend you take that drawing, xref attach the segmented drawing, and carefully zoom and pan to inspect all the curves.  Keep in mind it is processing purely based on that mathematical process and could create an arc where it is not intended to be.

Let me know when you obtain the CGEOCS name to use.

[Pointdump]

Hi Terry,

That one looks good. EPSG:3760 HARN/HI.HI-3Fa

Dave

[Chris_Baze]

Thanks @Pointdump! @TerryDotson, any updates? Also I'm wondering if there's a way to get the true curves in straight from ESRI rather than having to recalculate them. My understanding is that the geodatabase contains true curves, but cannot be directly imported to Civil 3D.

[TerryDotson]

@TerryDotson, any updates?

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As I said at the end of post #7, I'm waiting until you give me an Autodesk CS name string as returned by CGEOCS since it's projecting from WGS84, to avoid having to process it more than once.

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Also I'm wondering if there's a way to get the true curves in straight from ESRI rather than having to recalculate them.

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There is no consideration for arc segments in the Shapefile spec, unless I (and others) have missed something.  All they would have needed would have been a bulge factor (double) on each point like the AutoCAD Polyline.  As far as our tool, it makes sense to run it against the polyline object as there is more than one way to get to the segmented state.

My understanding is that the geodatabase contains true curves, but cannot be directly imported to Civil 3D.

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Do you have any links to details on this as we also have been working on GDB import/export?

Again, give me a CGEOCS string and I'll process the shapefile import to gen curves.

[Chris_Baze]

Thanks, confirming that CGEOCS = "HARN/HI.HI-3Fa" is what I need

Geodatabase:

https://www.loc.gov/preservation/digital/formats/fdd/fdd000293.shtml 

"It also supports advanced feature types such as geometric and logical networks, true curves"

Shapefile:

https://www.loc.gov/preservation/digital/formats/fdd/fdd000280.shtml

"Since circular arc curves are not supported in the format, existing circular arc curves will be transformed to simple line features with closely spaced vertices rather than as true arcs."

[TerryDotson]

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... confirming that CGEOCS = "HARN/HI.HI-3Fa" is what I need

I'm processing it right now, the latest revision is a little slower (for now) and there are a lot of parcels, will post when finished.

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Geodatabase:

https://www.loc.gov/preservation/digital/formats/fdd/fdd000293.shtml 

"It also supports advanced feature types such as geometric and logical networks, true curves"

I have downloaded the GDB version of your dataset and walking through the data looking for curve information.

[TerryDotson]

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Geodatabase:

https://www.loc.gov/preservation/digital/formats/fdd/fdd000293.shtml 

"It also supports advanced feature types such as geometric and logical networks, true curves"

I downloaded and processed the GDB of this dataset.  Attempts to obtain curve information in debug threw an exception and when I processed the dataset with our standard driver, I also see the short segment vertices.  I really don't think those short segment coordinates would exist if there were curve definitions present.  So, in summary while it looks like GDB format could support curves, I don't think your dataset contains that information.

[TerryDotson]

... confirming that CGEOCS = "HARN/HI.HI-3Fa" is what I need

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Sorry for the delay.  Initially we approached this assuming that one parameter would be acceptable for the entire file.  However, upon inspection we found that segments in different areas of the drawing varied significantly, some up to 5 time longer than others in a different area, this required some revisions in the tool, basically evaluating each parcel to determine the estimated segment distance for parcel.

Attached are parcels where we detected curves and converted them.  Insert this onto your own import and zoom in and carefully evaluate the results. Where the conversions are acceptable you can erase the old segmented polylines and change the color back to bylayer.

Again, I downloaded the GBD offered for your project and while it appears that the GDB format can support polylines segments with true curves, your agency did not appear to embed that data in the download.  If you can confirm otherwise or find a data set that does contain true arcs, please post back with the link.

[Chris_Baze]

Wow, impressive! It appears that all parcels without curves have been omitted. What's the easiest way to include them so I can review a complete data set?

[TerryDotson]

Attached is the modified parcels along with those not changed (no short segments).  Note that one parcel arc flipped causing the arc to grow out of proportion.  One out of 172,000 is not bad but we will try to determine why as soon as possible, in the meantime you can manually fix.

[samir.rezk]

Hi @Chris_Baze 

Depending on if you have an available Esri Single User license on your computer, you may be able to connect to ArcGIS FGDB in Civil 3D (AutoCAD Map 3D); The geometry is initially added as Map Features, then we can extract AutoCAD geometry from it, when using the MAPEXTRACTFEATUREGEOMETRY curves are maintained same as what's available in the FGDB.

This workflow is depended on Esri license requirements per article:

• What specific type of Esri license is needed to connect to a File Geodatabase in AutoCAD Map 3D or C...

Here are screenshot of the process:

This method will create the geometry, we would need to create a workflow to copy the object data if you need to bring in the attribute information as well. 

Hope this helps,

[Chris_Baze]

@samir.rezk I finally got my hands on a ArcGIS Pro license to test this out, but when I connect to the .gdb file nothing happens. Is there something I need to set up before I can successfully connect to the Geodatabase file?

[samir.rezk]

Hi @Chris_Baze 

Esri requires the software to be activated locally on the machine via a Single-Use License. AutoCAD Map FDO Connection will not authenticate with a Named User ArcGIS Pro activation.

See this link for guidance on converting  a license: Convert Named User licenses to Single-Use ArcGIS Pro | Documentation

As an example, check to see in your ArcGIS Pro settings how the software is activated:

Hope this helps,