[postgis-devel] Tiny WKB

Nicklas Avén nicklas.aven at jordogskog.no
Wed Mar 6 03:52:28 PST 2013

>It's not in order to store lat/long, but in order to get a better
>resolution than 360x180, right ? It's a matter of choosing a resolution,
>more than a number of digits.

Ok, I think I get what you mean

>GEOJson uses the concept of "quantization" as the number of distinct
>values each ordinate can take.

But the "percision" value in geojson, isn't that also number of decimals? ST_AsGeoJSON(geom,1) seems to give a result with 1 decimal.

 The format encodes the scale and offset,
>right ?

yes, you are right. in the header it stores "precision" in 4 bits, like 2 for instance.
That means it multiplicates the offset from last coordinate with 100, and vice verse at client side.

But it is not intended to be used at different scales. Isn't one of the big pros with vektor data that it can be used all over the range as long as it keeps "enough" details.

Leaflet for instance have a functionality called smoothFactor, that, if I understand it right, simplifies the geometries at render time.

I will try to read more about it to understand pros and cons by different concepts.



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