SpatialDB Advisor: manifold_tips

Simplification and Gridding

· 667 days ago by Simon Greener

Simplifier is a Manifold Map script that implements a set of different methods for topological simplification of a planar-enforced polygon drawing.

The code (map file) can be downloaded here

To understand what it does see the presentation on Gridding and Simplification (Presentation on techniques for modifing/splitting of large polygons that demonstrate slow performance when being geoprocessed (intersected).) I gave at the Oracle Forum in Sydney in August 2008.

Tip #1 - Extracting the Spatial Extent of an Image and Saving in a Drawing

· 1393 days ago by Simon Greener

This tip comes from a question Atelier Cassini asked on the Directions Magazine discussion list. He writes:

"I would like to create a box drawing around an image. Do I need to know the exact dimension of that image or can I draw it automatically?"

While one cannot do this automatically, one can use a single SQL SELECT statement to extract the boundary of an image and write it into a drawing component.

Let us assume that the target drawing is called "MyDrawing" and that the source image is called "SpatialDBAdvisor".

The method I recommended was to create a new Query component and then add the following SQL SELECT statement into that component.

INSERT INTO MyDrawing ([Geom (I)])
SELECT Project(
         AssignCoordSys(
           CGeom(CGeomWKB(
                      "POLYGON(("&min([Easting (I)])&" "&
                                 min([Northing (I)])&", "&
                                 min([Easting (I)])&" "&
                                 max([Northing (I)])&", "&
                                 max([Easting (I)])&" "&
                                 max([Northing (I)])&", "&
                                 max([Easting (I)])&" "&
                                 min([Northing (I)])&", "&
                                 min([Easting (I)])&" "&
                                 min([Northing (I)])&"))")),
           CoordSys("SpatialDBAdvisor" AS Component)),
           CoordSys("MyDrawing" As Component))
FROM [SpatialDBAdvisor]

If your image data is in geographics (ie Latitude/Longitude) then you should replace the Easting and Northing intrinsics with their Longitude/Latitude equivalents.

I hope this is useful.

Manifold GIS - Tips and Tricks

· 1393 days ago by Simon Greener

Folks, for a client GIS I use Manifold GIS. It is cheap, powerful, and if one normalises its functionality by cost (ie the ratio functionality/cost), it is the best value client GIS on the market.

For a good understanding of its power one should read Dr Arthur Lembo Jnr’s Comparison with ArcGIS document. This document was compiled by Cornell University students under his supervision. You may want to have a look at it, as it graphically illustrates how to do certain tasks in both technologies. In effect it is a side-by-side of certain “common” GIS functions.

This page will be dedicated to simple Tips and Tricks I have found useful when using Manifold GIS. Some have been gleaned from Manifold-L the Directions Magazine hosted discussion list. Others from GeoReference the Manifold user forum hosted by Manifold.Net.

>>Manifold GIS - Tips and Tricks