[raster] Provide some predefined common usage userfunc for ST_MapAlgebraFctNgb

[pracine]

Now that we have ST_MapAlgebraFctNgb we might want to provide some predefined user functions like ST_Max, ST_Min, ST_Sum, ST_Distinct, ST_Mean, ST_StdDev, ST_Range, ST_Quantile, ST_Median, ST_Majority, ST_Minority, ST_Slope, ST_Aspect…

We might want to systematically change the prefix or add a suffix (I would suggest '4MA' i.e. 'for MapAlgebra') to the function names so we know were written to be used with ST_MapAlgebraFctNgb. e.g. ST_Slope4MA()

[dzwarg]

Replying to pracine:

Now that we have ST_MapAlgebraFctNgb we might want to provide some predefined user functions like ST_Max, ST_Min, ST_Sum, ST_Distinct, ST_Mean, ST_StdDev, ST_Range, ST_Quantile, ST_Median, ST_Majority, ST_Minority, ST_Slope, ST_Aspect…

We might want to systematically change the prefix or add a suffix (I would suggest '4MA' i.e. 'for MapAlgebra') to the function names so we know were written to be used with ST_MapAlgebraFctNgb. e.g. ST_Slope4MA()

It may make sense for ST_Slope and ST_Aspect to be their own functions that wrap ST_MapAlgebraFctNgb, since the neighborhood is fixed at 3x3.

[dzwarg]

Added in r8262:

• ST_Max4ma
• ST_Min4ma
• ST_Sum4ma
• ST_Mean4ma
• ST_Range4ma

Added in r8264:

• ST_Slope

Added in r8265:

• ST_Aspect

Added in r8274:

• ST_Hillshade

[dzwarg]

pracine:

Can you elaborate on ST_Quantile? I'm not familiar with what kind of neighborhood operation that would be.

[pracine]

Bborie is the true reference for quantiles. You can look at the examples in wikipedia: ​http://en.wikipedia.org/wiki/Quantile

I would make it low priority as the other ones are more common: ST_Distinct, ST_StdDev, ST_Median, ST_Majority, ST_Minority…

[dustymugs]

Agree with making it a low priority to 2.1.

[pracine]

I postpone it to 2.1 since only ST_Quantile, ST_Median, ST_Majority and ST_Minority are missing and are of lower priority.

[strk]

This seems to be done, reading ​http://postgis.net/docs/RT_reference.html#Raster_Processing_MapAlgebra_Callbacks

Feel free to reopen (maybe even a new one) for specific new enhancements