44 lines
1.0 KiB
Markdown
44 lines
1.0 KiB
Markdown
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Function to "safely" transform to webmercator. This function is most useful for rendering custom geometries using the CartoDB tiler. Often, transforming a projection like WGS84 can cause issues with extents beyond what are actually valid in webmercator, this attempts to fix those issues.
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#### Using the function
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Using a box that is nearly the full globe,
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```sql
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ST_SetSRID(
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ST_Envelope(
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ST_Collect(
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ST_MakePoint(-180,60),
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ST_MakePoint(180,-60)
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)
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),
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4326
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)
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```
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We can then convert it to a renderable webmercator geometry.
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```sql
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SELECT CDB_TransformToWebmercator(
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ST_SetSRID(
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ST_Envelope(
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ST_Collect(
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ST_MakePoint(-10,60),
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ST_MakePoint(300,-60)
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)
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),
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4326
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)
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)
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```
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Would give you back a single valid rectangle in webmercator. Since a longitude of 300 would convert to an unallowed webmercator coordinate, it gets clipped first. Valid extent is WGS84 (-180, -89, 180, 89)
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#### Arguements
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CDB_TransformToWebmercator(geom)
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* **geom** geometry
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