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Re: Ellipse Data Type? Best practices for elliptical data? [Oracle 9i Spatial]

From: C Wilks <cjwilks_at_hotmail.com>
Date: Tue, 18 May 2004 17:37:02 GMT
Message-ID: <2Rrqc.83303$sK3.35506@nwrddc03.gnilink.net>


> Are you trying to set up a new datum or coordinate system? Oracle does

I will just be using a standard geodetic spatial reference system, probably WGS84 from what I can gather so far. I'm just trying to store geodetic ellipses, and then compare them with other shapes using the standard spatial predicates.

For each ellipse entered, I'll know the center lat/lon, major/minor axes, and rotation angle.

In 10g - it appears there is a function SDO_UTIL.ELLIPSE_POLYGON() that lets you approximate an ellipse using this information. Does anyone know what kind of SDO_GEOMETRY this function generates? (i.e. how does it approximate the ellipse?).

In 9i - it looks like you'd have to do the calculations manually to determine enough perimeter coordinates to create a polygon out of multiple arcs. Does anyone know how to do these calculations? and/or could you point me to an article or URL that would shed some light on it? Received on Tue May 18 2004 - 12:37:02 CDT

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