Hi
> If all we need to do is replace
> calls to getCoordinate with getCentroid, I can prepare a patch for
> this as well.
>
I don't know who (which plugin) use it, but I think that with the
current implementation, the centerOfMass of a set of polygons made of a
single regular polygon will return a point of the boundary (which is not
what people usually call a center)
Michaël
> 2009/6/24 Michaël Michaud <michael.mich...@free.fr>:
>
>> Hi,
>>
>> I think you're right again.
>> For a better result with non puntal geometries, one should use
>> getCentroid instead of getCoordinate in getCenterOfMass method
>> One could also compute something closer to a center of mass by using the
>> area or the length of the feature as the "mass" of each feature
>> Of course, computing getCentroid + getArea + getLength can take much
>> more time than a single getCoordinate()
>>
>> Michaël
>>
>>> While we are on the topic, could you guys look at the getCenterOfMass
>>> method in the same class. Its supposed to act like the
>>> Geometry.getCentroid method, but for a group of Feature objects.
>>> However, I didn't see any use of the getCentroid method on the member
>>> feature geometries from within the method. There is some math going on
>>> in the method using coordinates obtained via the getCoordinate()
>>> method, but I don't think it does what it is supposed to.
>>>
>>> I think we should clarify the purpose of the method in the javadoc
>>> comment, or perhaps discuss alternate implementations of the
>>> getCenterOfMass method. This might be a good discussion for the JTS
>>> mailing list.
>>>
>>> I know you guys are busy. Only peek if you have time. I'll have a
>>> revamped FeatureCollectionTools class ready by the end of the week I
>>> hope. There should be some stuff in there I can port back to OJ after
>>> you guys take a look. The revamped class will include a method to
>>> compare the equality of FeatureCollections, which should be handy for
>>> unit testing.
>>>
>>> SS
>>>
>>> On Wed, Jun 24, 2009 at 10:44 AM, Larry Becker<becker.la...@gmail.com>
>>> wrote:
>>>
>>>
>>>> Yes, you are right. The getCoordinate() only works when looping through a
>>>> single feature's points.
>>>>
>>>> Larry
>>>>
>>>> On Wed, Jun 24, 2009 at 12:12 PM, Sunburned Surveyor
>>>> <sunburned.surve...@gmail.com> wrote:
>>>>
>>>>
>>>>> Thanks for the responses Larry and Michael. I have attached a text
>>>>> file with my modified method. (Note: There are other changes to my
>>>>> method that I would not include in the patch.) I believe that the use
>>>>> of getCoordinate method should be replaced with the
>>>>> getEnvelopeInternal method.
>>>>>
>>>>> But I could be wrong.
>>>>>
>>>>> SS
>>>>>
>>>>> On Wed, Jun 24, 2009 at 6:22 AM, Larry Becker<becker.la...@gmail.com>
>>>>> wrote:
>>>>>
>>>>>
>>>>>> Hi SS,
>>>>>>
>>>>>> If you are talking about this code, it looks like it works to me:
>>>>>>
>>>>>> public static Envelope getEnvelopeForFeatures(Feature[] features){
>>>>>> Envelope env = null;
>>>>>> Feature feat;
>>>>>>
>>>>>> for (int i=0; i<features.length; i++){
>>>>>> feat = features[i];
>>>>>> if (env==null){
>>>>>> env = new Envelope(feat.getGeometry().getCoordinate());
>>>>>> } else {
>>>>>> env.expandToInclude(feat.getGeometry().getCoordinate());
>>>>>> }
>>>>>> }
>>>>>>
>>>>>> return env;
>>>>>> }
>>>>>>
>>>>>> regards,
>>>>>> Larry
>>>>>>
>>>>>> 2009/6/24 Michaël Michaud <michael.mich...@free.fr>
>>>>>>
>>>>>>
>>>>>>> Hi,
>>>>>>>
>>>>>>>
>>>>>>>> I believe there may be a bug in the getEnvelopeForFeatures method of
>>>>>>>> the FeatureCollectionTools class. It uses the Geometry.getCoordinate
>>>>>>>> method when it should use the Geometry.getEnvelopeInternal method.
>>>>>>>> This may result in the calculation of an envolope that does not
>>>>>>>> include the envelope of all features.
>>>>>>>>
>>>>>>>>
>>>>>>>>
>>>>>>> I think you're right. Using getCoordinate to compute an envelope is not
>>>>>>> correct.
>>>>>>> Feel free to fix it. You've got a correct implementation in
>>>>>>> com.vividsolutions.jump.feature.FeatureDataset.getEnvelope().
>>>>>>>
>>>>>>> Michaël
>>>>>>>
>>>>>>>
>>>>>>>> When I get my modified version of the getEnvelopeForFeature method
>>>>>>>> tested I will submit a patch.
>>>>>>>>
>>>>>>>> SS
>>>>>>>>
>>>>>>>>
>>>>>>>>
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>>>>>>>>
>>>>>>>>
>>>>>>>>
>>>>>>>>
>>>>>>>>
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>>>>>>>
>>>>>> --
>>>>>> Larry Becker
>>>>>> Integrated Systems Analysts, Inc.
>>>>>>
>>>>>>
>>>>>> ------------------------------------------------------------------------------
>>>>>>
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>>>>>>
>>>>>>
>>>>>>
>>>>>>
>>>>> ------------------------------------------------------------------------------
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>>>>>
>>>>>
>>>>>
>>>> --
>>>> Larry Becker
>>>> Integrated Systems Analysts, Inc.
>>>>
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