[Manifold-l] On screen digitizing of curves

[Springfield Harrison]

Hello Pat:

         Thanks for your thoughtful response.  I don't know enough about 
the ESRI capabilities to comment but I suspect you're right, especially the 
last paragraph.

         The tight digitizing works well, the steadier the hand the 
better.  However, segmentizing does not seem to add any accuracy, just more 
nodes on the existing line segments (I may be mis-using the word "segment" 
here).  Under certain conditions, Spline may satisfactorily smooth out a 
series of line segments.

         Thanks again, Spring


At 06/11/2007 03:05 PM Tuesday, Pat Waggaman wrote:
>Interesting if one of the sages pops up and says that "curves" can be 
>created in ESRI software.  Perhaps it is so, I suspect that at some point 
>the creation of a "curve" runs into the mathematical expediency of Epsilon 
>in its representation; particularly when said curve is calculated by a 
>digital processor.
>
>Meantime what I´d do is tightly digitize the orthophoto and, using the 
>Segmentize control reduce the segment length between your points to 
>somewhere between a couple of centimeters and the beautiful 1/1,000,000 
>meter resolution that can be achieved with the Manifold grids.
>
>And then you´re in the spectacular negotiating position of asking your 
>client to balance the cost of the ESRI system with the nanometer error 
>that you are introducing.  At some point in the discussion it will arise 
>that the errors you introduce are orders of magnitude less than the 
>potential errors created by the difficulty of the ESRI operator in 
>locating the center points, from which the curves will be created.
>
>Have at it lad.
>
>Pat
>
>
>At 18:41 06-11-2007, Springfield Harrison 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
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: http://www.directionsmedia.net/pipermail/manifold-l/attachments/20071106/52a1475b/attachment-0001.html