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artlembo

3,096 post(s)
#28-May-18 20:06

I've attempted to insert points into a drawing (that is defined as EPSG:2261):

INSERT INTO [drawing] (geom)

VALUES

(

    CoordConvert(CALL CoordConverterMake(

    CoordSystemEPSG(4326), 

    CoordSystemEPSG(2261)), 

    GeomMakePoint(VectorMakeX2(-76.5,42.444))

 )

this query inserts the point at -79.5, 39.97.

What I really want to do is put a lon/lat value into a drawing. The query above hopes to take that lon/lat as EPSG:4326 and convert it to EPSG:2261, and then insert it in. Perhaps I am approaching it wrong.

I've attached a .map file with a EPSG:2261 coordinate definition.

Attachments:
coordconvert.map

tjhb

8,348 post(s)
#28-May-18 22:42

Art,

I haven’t tested, but I believe you have target and source CS reversed.

Target comes first, then source.

artlembo

3,096 post(s)
#29-May-18 00:18

thanks, Tim. That was part of it. I reversed them, and the new coordinate is now:

393.5 W, 114.12 S - ha, ha. So, that is way off.

But, I changed the coordinate order- I had the order of the coordinates wrong. It has to be:

VectorMakeX2(42.44,-76.5)

tjhb

8,348 post(s)
#29-May-18 00:43

Oh right, 4326 is YX! I hadn’t thought of that.

Two backflips.

artlembo

3,096 post(s)
#29-May-18 00:51

I was actually surprised. Lat/Lon is YX, but I thought EPSG:4326 was XY.

tjhb

8,348 post(s)
#29-May-18 01:23

I think Manifold’s internal “Latitude / Longitude” projection is XY. I don’t think any of the native Manifold CS uses YX.

Dimitri

5,083 post(s)
#29-May-18 08:37

You can see what it is for sure by using it for a drawing, and then opening the Coordinate System dialog. It reports:

{ "Name": "Latitude \/ Longitude", "System": "Latitude \/ Longitude", "Base": "World Geodetic 1984 (WGS84)", "Axes": "XYH", "MajorAxis": 6378137, "Eccentricity": 0.08181919084262149, "Unit": "Degree", "UnitLatLon": true, "UnitScale": 1, "UnitShort": "deg" }

Now, compare that to a different coordinate system, "WGS 84 (EPSG:4326)" using the filter box set to 4326 in the EPSG tab:

{ "Name": "WGS 84 (EPSG:4326)", "System": "Latitude \/ Longitude", "Base": "WGS 84 (EPSG:4326)", "Axes": "YX", "MajorAxis": 6378137, "Eccentricity": 0.08181919084262149, "Unit": "Degree", "UnitLatLon": true, "UnitScale": 1, "UnitShort": "deg" }

Similar, but EPSG:4326 flips axis order.

artlembo

3,096 post(s)
#29-May-18 13:44

Thanks, Dimitri. I love it when the semester ends, I get to return back to different projects I've had on the back burner. This is part of finishing off the How do I do that in Manifold 9 GIS SQL. It's allowing me a much better understanding of 9, and also giving me more confidence of what capabilities are in 9.

There are about 6 or 7 things left (mostly raster), and then we'll have confidence that 9 can do everything in the USGS definitions. That is a great way to evaluate the core capabilities of a GIS software product.

Of course, the next this is to create a book called How fast can I do that in GIS, comparing serial vs. parallel computation - ha, ha!

Dimitri

5,083 post(s)
#29-May-18 15:40

There are about 6 or 7 things left (mostly raster),

Send a personal email to you-know-who with a brief list of those 6 or 7 things as short bullets. :-) You've probably submitted them all as suggestions and such but I know right now there is a big discussion on immediate next steps where your personal counsel would be even more valued than it always is.

I, personally, like the idea of adding just a few more things to close the loop on some major capabilities and you get a whole lot of capability for so many things all at once. Raster is a good opportunity. Kriging, that is, vector to raster, is in one of the upcoming builds very close now, and with just a handful more things like that we'll have a dramatically more useful tool for rasters. Your counsel on that handful would be great.

This reminds me of a town I once knew in a nice climate where people really wanted to commute to work by bicycle, but the part of town where all the office parks were was on the other side of railroad tracks from where everybody lived. There were plenty of bike paths on either side of the tracks but the tracks in the middle made it hard to commute. All they needed was just one underpass for bicycles.

Well, one day they put in that underpass and, like magic, got about a 10,000 percent increase in bike use. The town went from "can't use a bike here" to "wow! I bicycle everywhere!" overnight.

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