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I need to remove Z dimension on spatial column (ST_GEOMETRY) with Esri on Oracle using the PL/SQL packages

I need to do the following, but using the ESRI PL/SQL packages on Oracle.

I have used a couple of the packages such as SDE.ST_GEOMETRY_OPERATORS, however I am unsure if doing the below (removing Z) is possible in PL/SQL.

There are directions of how to do this in ArcMap:

https://support.esri.com/en/technical-article/000010389

  • Browse to ArcToolbox > Conversion Tools > To Geodatabase.
  • Open the Feature Class to Geodatabase (multiple) tool.
  • Add all the feature classes into the Input Feature Class parameter.
  • Select an Output Geodatabase.
  • Click the Environments button at the bottom of the tool dialog box.
  • Expand the General Settings.
  • For the parameter, Output has Z Values, change the value to Disabled.
  • For the parameter, Output has M Values, change the value to Disabled.
  • Click OK in the Environments dialog box.
  • Click OK to execute the geoprocessing tool.

How can I do the equivalent in PL/SQL?

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  • That is what I want to do. I am trying to ETL esri tables into an oracle data warehouse with sdo_geometries through an oracle db_link.
    – Doc
    Aug 31, 2020 at 11:55
  • Also I have an oracle plsql function which will convert the st_geometry into a wkt well know text. I also have another plsql function to pull the wkt clob through the dblink. The only thing I could not get via plsql was the conversion to a tableau (resorting) friendly 2d layer.
    – Doc
    Aug 31, 2020 at 11:58
  • I meant reporting tool friendly ( such as tableau ) by removing the z dimension
    – Doc
    Aug 31, 2020 at 12:00
  • My experience with Z-enabled feature classes has been that the Z values are often in the feature classes by mistake; they're not actually used. Do you have the option of asking the data owner to remove the Z-dimension from the feature classes?
    – User1974
    Sep 2, 2020 at 2:09
  • I have reporting tools such as Tableau and Thoughtspot. They only use 2D geometries. That is why I hope to remove the Z attributes. I am not sure if Oracle can accept the ESRI exported Z WKT's (Well known text). I have a regex expression to remove the z dimensions from the string, but I would MUCH prefer do it with pl/sql via a transform type of function ...such as ESRI's sde.st_transform(shape,4269) or Oracle's SDO_CS.TRANSFORM(SHAPE,4269)
    – Doc
    Sep 9, 2020 at 2:18

1 Answer 1

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I've created a test SDE.ST_GEOMETRY polyline feature class that has Z coordinates. This is what the WKT text looks like:

select
    sde.st_astext(shape)
from
    st_geom_z


SDE.ST_ASTEXT(SHAPE)                                                            
---------------------------------------------------------
LINESTRING Z ( 0.0 0.0 1.0, 10.0 20.0 2.0, 30.0 40.0 3.0)
                        ^              ^              ^

You'll notice that the WKT has a " Z " in the prefix: LINESTRING Z (). I don't think Oracle SDO_GEOMETRY supports that syntax. I think it needs it to be like this: LINESTRING ().


Steps:

  1. We can remove the Z from the WKT string using the REPLACE function.
  2. Then we can convert the WKT to SDO_GEOMETRY.
    • Unfortunately, ST_GEOMETRY doesn't have a function for removing Z coordinates from geometries. So we'll do it using SDO_GEOMETRY instead.
  3. We'll remove the Z's from the SDO_GEOMETRY using the SDO_CS.MAKE_2D function.

.

select
  sdo_cs.make_2d(
    sdo_geometry(
      replace(upper(sde.st_astext(shape)),'LINESTRING Z','LINESTRING'))) sdo_geom_no_z
from
  st_geom_z

SDO_GEOM_NO_Z                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                              
------------------
SDO_GEOMETRY(2002, NULL, NULL, SDO_ELEM_INFO_ARRAY(1, 2, 1), SDO_ORDINATE_ARRAY(0, 0, 10, 20, 30, 40))

Now, the SDO_GEOMETRY vertices only have X&Y coordinates, not Z.

SDO_UTIL.TO_WKTGEOMETRY(SDO_GEOM_NO_Z)                                          
------------------------------------------
LINESTRING (0.0 0.0, 10.0 20.0, 30.0 40.0)

Note: That query will also remove M-values too (not just Z values).


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