Most likely ArcMap just computes a point which is close to the line using
some double-precision arithmetic computation. I don't think even ESRI can
defy the laws of Floating-Point arithmetic. The high-precision spatial
predicates that JTS uses show the point as not lying on the line.
On Mon, Dec 8, 2014 at 11:23 PM, Cristian Cerb <[email protected]> wrote:
> Thank you. I will try your suggestion. The point was placed on the segment
> using ArcMap, so it is within the segment, beyond any doubt.
>
> Sent by De Christian
>
> On Dec 8, 2014, at 7:13 PM, Martin Davis <[email protected]> wrote:
>
> It's pretty unlikely for a point to lie exactly on a line segment where
> the endpoints have that much precision. Why do you think it does?
>
> Instead, consider using a small tolerance value when using the
> distancePointLine test (following the same principle often used when
> testing FP numbers for "equality":
> http://floating-point-gui.de/errors/comparison/)
>
> On Mon, Dec 8, 2014 at 12:38 PM, Jik Le Shoog <[email protected]>
> wrote:
>
>> I must do something wrong or there is a bug in JTS:
>>
>> I have a point that falls with a segment 100%, it does not overlap any
>> segment vertice.
>>
>> //Sample points that cause failure
>>
>> //point.getGeometry().toText(): POINT (1189813.2298558373 1282137.
>> 5104076413)
>> //line.getGeometry().toText(): LINESTRING (1190117.3577566557
>> 1282021.6521597095, 1189478.994760329 1282264.8380630743)
>>
>> //point.getGeometry().toText(): POINT (1189518.6390980254
>> 1282448.001756093)
>> //line.getGeometry().toText(): LINESTRING (1189426.304481268
>> 1282287.1301042158, 1189622.879753152 1282629.6169181187)
>>
>> Java code:
>>
>> Coordinate pointCoord = point.getGeometry().getCoordinate();
>> Coordinate[] lineCoords = line.getGeometry().getCoordinates();
>>
>> Any of the following if-s evaluate their condition to false, when I
>> expected true:
>>
>>
>> LineSegment lineSegment = new LineSegment(lineCoords[0], lineCoords[1]);
>> if (lineSegment.distance(pointCoord) == 0) {
>>
>> if (CGAlgorithms.distancePointLine(pointCoord, lineCoords[0],
>> lineCoords[1]) == 0) {
>>
>> if (CGAlgorithms.isOnLine(pointCoord, lineCoords)) {
>>
>>
>> Any help, please? I consider all those 3 methods would be appropriate for
>> determining if point within segment.
>>
>>
>> thank you.
>>
>>
>>
>>
>>
>> ------------------------------------------------------------------------------
>> Download BIRT iHub F-Type - The Free Enterprise-Grade BIRT Server
>> from Actuate! Instantly Supercharge Your Business Reports and Dashboards
>> with Interactivity, Sharing, Native Excel Exports, App Integration & more
>> Get technology previously reserved for billion-dollar corporations, FREE
>>
>> http://pubads.g.doubleclick.net/gampad/clk?id=164703151&iu=/4140/ostg.clktrk
>> _______________________________________________
>> Jts-topo-suite-user mailing list
>> [email protected]
>> https://lists.sourceforge.net/lists/listinfo/jts-topo-suite-user
>>
>>
>
------------------------------------------------------------------------------
Download BIRT iHub F-Type - The Free Enterprise-Grade BIRT Server
from Actuate! Instantly Supercharge Your Business Reports and Dashboards
with Interactivity, Sharing, Native Excel Exports, App Integration & more
Get technology previously reserved for billion-dollar corporations, FREE
http://pubads.g.doubleclick.net/gampad/clk?id=164703151&iu=/4140/ostg.clktrk
_______________________________________________
Jts-topo-suite-user mailing list
[email protected]
https://lists.sourceforge.net/lists/listinfo/jts-topo-suite-user
