Coordinate Systems

I'm not sure I have any really slick solutions, but our usual method is to assign the local system in our survey drawing, and then create separate drawings for our aerials, and for our GIS data, and assign the appropriate state plane zone to those drawings.

Xref the aerial and GIS drawings into the survey, and they are reprojected to the local system. That way we don't have to worry about aligning or rubbersheeting, or scaling and rotating blocks or images whenever we need to add any of the state plane data. Just drop it into the xref, save and reload in survey base. Plus it keeps the survey base drawings clean (and keeps the engineers from assuming those digitized utility lines are actually surveyed).

Of course, as I write this, I don't know if C3D already has the Oregon LDPs. But you could certainly input the projection parameters and create a coordinate system if not...

@rover83

Hmmmmm... I thought I tried that. I'll try again.

For the record, OCRS is not supported natively, but there are replacement files available that include it. Apparently it is included in the 2021 version.

Have you tried ADEQUERY within Civil3d? You can set a projection in a "new" drawing, then reproject and transform other drawings, images, shapefiles to your current projection. I haven't used it in a while but it works quite well.

I know nothing about CAD or Carlson or any of that stuff, but if I wanted to get Oregon North SPC into OCRS Portland or vice versa, I would try a little experiment.

The Oregon North state plane coordinates for RD3272 are 702,755.63N, 7,626,913.54E, in International Feet. Are the coordinates below correct for OCRS Portland?

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@mathteacher

Oregon North: 702755.6300?ÿ ?ÿ ?ÿ 7626913.5400 (Int'l Feet)?ÿ

Lat/Long:?ÿ ?ÿ ?ÿ ?ÿ45?ø34'20.381059"?ÿ ?ÿ122?ø44'47.231338"
?ÿ ?ÿ ?ÿ ?ÿ ?ÿ ?ÿ ?ÿ ?ÿ ?ÿ ?ÿ ?ÿ45.57232807?ÿ ?ÿ ?ÿ ?ÿ ?ÿ 122.74645315

OCRS-PDX:?ÿ ?ÿ ?ÿ190415.7788?ÿ ?ÿ ?ÿ328992.3248 (Int'l Feet)

@norman-oklahoma

So, the Northing hits to the nearest hundredth and the Easting is different by 2 hundredths of a foot. But my lat/lon is 10 significant digits, so conceivably, the difference is rounding. I'll use more digits and see what happens.

More digits here:

My thought was to get both sets of points on the same projection by creating one input file using mapping software. DNRGPS is easy and it accepts text file data, so you could read Oregon North data, convert it to lat/lon?ÿ and then to OCRS Portland in the mapping software. Append that to the other file and then read it into CAD or Carlson or whatever.

The Oregon North .prj is in the system; the WKT version of OCRS Portland is below. It goes into DNRGPS as a custom file.

PROJCS["unnamed",
    GEOGCS["GRS 1980(IUGG, 1980)",
        DATUM["unknown",
            SPHEROID["GRS80",6378137,298.257222101]],
        PRIMEM["Greenwich",0],
        UNIT["degree",0.0174532925199433]],
    PROJECTION["Lambert_Conformal_Conic_1SP"],
    PARAMETER["latitude_of_origin",45.5],
    PARAMETER["central_meridian",-122.75],
    PARAMETER["scale_factor",1.000002],
    PARAMETER["false_easting",328083.9895],
    PARAMETER["false_northing",164041.9948],
    UNIT["Foot (International)",0.3048],
    AUTHORITY["epsg","6855"]]

Point is, that GIS software can be used for things other than screwing up property lines and it can output very accurate figures apart from maps. I don't have the patience to learn complicated stuff anymore, so I just use DNRGPS and output whatever file I need; text, KML, whatever.

Nice exercise; thanks for sharing.

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