[Manifold-l] On screen digitizing of curves

[Simon Greener (SpatialDB Advisor)]

Yes, ESRI geodatabases have curves (as does Oracle Locator), but over time  
the curves in geodatabases can lose their radius as snapping occurs. Get  
your potential customer to search the ESRI forums about these problems.  
(Though they might be fixed in ArcGIS 9.2.)

And, yes, Manifold cannot create or edit data with curves. Manifold  
strokes any curved line segments in an Oracle Locator database.

Pat Waggaman's observations about stroking curves are correct: but I would  
say get someone to write you a tool for 8.0 that asks for three points  
that define a circle - start and end point of the curve and either the  
centre of the circle or another point on the circumference - and then  
programmically creates a stroked linestring using a user entered  
arc-to-chord separation (for cadastral data a separation of 3mm is  
sufficient but you could reduce it to 1mm). The cost of writing this tool  
+ Manifold GIS would be far less than purchasing ArcGIS.

I have the COGO code to do all this for Oracle and could port it to  
VBScript and Manifold quite easily but I would want payment for doing so  
as I work for myself!

BTW what is OSD in your email?

regards
Simon
On Wed, 07 Nov 2007 08:41:20 +1100, Springfield Harrison  
<stellargps at shaw.ca> wrote:

>          From the forum:
>
> Hello:
>
> A potential client needs on screen digitizing of roads from an orthophoto
> but the curves cannot be line segments. Apparently the ESRI Geodatabase
> into which these data will go can define curves with a start, end and  
> radius.
>
> This may be so but how can OSD be used to create curves in Manifold, or
> anything else for that matter. I think OSD can only create straight
> segments joining mouse clicks. Even stream digitizing is a series of very
> closely spaced dots, I think.
>
> Can this actually be done as required by the proponent using OSD?
>
> Thanks very much, Springfield
>
>
>                             Spring Harrison
>                                        Stellar GPS & Mapping
>                                  103 - 9800 McDonald Park Road
>                                         Sidney, B. C. Canada
>
>                                           www.StellarGPS.ca
>
>                                   Voice, 24 hr: (250) 655-0764
>                                      Toll free: (888) 655-0764
>                                          Fax: (250) 654-0049
>



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