Update linestopolygons algorithm description #9784
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I didn't attach visualization (print screen) because it's a pretty long one in render. |
| - OUTPUT | ||
| - NOTE | ||
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| * - **Feature a**: Single line LineString |
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| * - **Feature a**: Single line LineString | |
| * - **Feature a**: Single segment LineString |
| Lines to polygons on linestrings | ||
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ | ||
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| Features with 3 or more vertices are expected on input: **start point - vertex/vertices - end point** |
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The first example contradicts this statement. And as I suggest later, I'd just merge concept of single and multiline segments together
| Lines to polygons on linestrings | |
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ | |
| Features with 3 or more vertices are expected on input: **start point - vertex/vertices - end point** |
| Generates a polygon layer from line layer, considering LineString geometry with three | ||
| or more vertices as polygon rings. Input LineString geometry doesn't need to close a loop, |
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Nitpicking.. Not really true because when you use a line with two vertices, you also get a polygon layer. Empty polygon geometry, as stated later, still a polygon layer.
| Generates a polygon layer from line layer, considering LineString geometry with three | |
| or more vertices as polygon rings. Input LineString geometry doesn't need to close a loop, | |
| Generates a polygon layer using as polygon rings the individual line features from an input line layer. | |
| Input LineString geometry doesn't need to close a loop, |
| algorithm will automatically connect last to first point when forming a polygon. | ||
| Result is always promoted to MultiPolygon. | ||
| LineString geometry that have less than three vertices will produce | ||
| new polygon features with **EMPTY** MultiPolygon geometry, attributes are kept. |
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| new polygon features with **EMPTY** MultiPolygon geometry, attributes are kept. | |
| new polygon features with **EMPTY** geometry. |
| The attribute table of the output layer is the same as the one of | ||
| the input layer. |
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| The attribute table of the output layer is the same as the one of | |
| the input layer. | |
| Attributes of the input line feature are ALWAYS kept in the output polygon geometry. |
And then I wonder if we need to repeat it for every example below
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| .. list-table:: | ||
| :header-rows: 1 | ||
| :widths: 30 30 40 |
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| :widths: 30 30 40 | |
| :widths: 30 30 40 | |
| :class: longtable |
This allows in the PDF build to have long tables split across pages
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| | **Output has a valid (empty) geometry.** | ||
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| * - **Feature b**: LineString with three vertices |
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Does the number of vertice/segments matters? It is more the situation of a not closed linestring with more than one segment, no?
| This can be fixed by using :ref:`qgisfixgeometries` algorithm with two possible scenarios: | ||
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| 1. *Fixing by structure repair method* - two parts will dissolve into MultiPolygon geometry with one part | ||
| 2. *Fixing by linework repair method* - equal to symmetrical difference of two parts which results MultiPolygon geometry with one part (doughnut shape in this case) |
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| 2. *Fixing by linework repair method* - equal to symmetrical difference of two parts which results MultiPolygon geometry with one part (doughnut shape in this case) | |
| 2. *Fixing by linework repair method* - equal to symmetrical difference of two parts which results in MultiPolygon geometry with one part (doughnut shape in this case) |
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| :width: 25 em | ||
| :align: center | ||
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| Two distinct LineStrings, one geometrically contained inside another |
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(here and below) Are LineString and MultiPolygon (written with that casing) pluralizable? How about
| Two distinct LineStrings, one geometrically contained inside another | |
| Two distinct line features, one geometrically contained inside another |
| - | **Feature e**: MultiPolygon | ||
| | **Feature f**: MultiPolygon |
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How does this render in HTML?
DelazJ
added
Processing Alg
Goal:
Create a better documentation for native LinesToPolygons processing algorthm.
Please review and suggest additional edits if needed.
After we finish final version, I will prepare similar one for native Polygonize algorithm.
Ticket(s): #