Fix/centroid #155
Fix/centroid #155
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… to 0 and then the result back. The first Point of the Geometry is used as the new origin. During the centroid calculation each Point is translated by subtracting the origin. At the end the resulting point is translated back by adding the origin.
…stems than cartesian. Remove undefined namespace. Add missing headers. Add a note about other coordinate systems. Add copyright info.
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Even though centroid() doesn't support other CS than cartesian because of lack of strategies I prepared the algorithm by disabling translation in other coordinate systems (see the NOTE in the code). I enabled the translation for all types of geometries, also non-Areal but I'm not sure is this is needed. EDIT: Another solution would be to enclose the translation inside a Strategy, so pass this origin Point into the But I'm probably as usual going to much ahead with all of this. I guess we could choose a lazy approach here, or rather change only the broken part. So translate only Areal Geometries inside the algorithm and leave everything else as it was before. |
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OK to merge this |
| areal_tag | ||
| >::type, | ||
| typename CSTag = typename cs_tag<Geometry>::type> | ||
| struct translating_transformer |
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Maybe this can go to another file
Add ctor taking Geometry to transformer. This allows to encapsulate the origin-retrieving-logic inside the transformer. Remove assign_origin() function.
Fix for Geometries containing big coordinates values.
During the calculation of a centroid the strategy may perform calculus using great values, e.g. add squares of coordinates, which greately increases the numerical error. This is related with #154.
The main idea is to move the Geometry closer to 0 and calculate the centroid for such Geometry. The new origin is the first Point of a Geometry. The translation is done on-the-fly as centroid is calculated. Then the resulting point is translated back.
The picture below shows the Polygon placed closer to 0 and further, plus their centroids before and after the fix.