H2 native raster functions

[nicolas-f]

• [x] raster::geometry
  • Convex hull of the raster (taking account of rotation)
• [x] ST_MetaData( RASTER ) ->ARRAY (Coordinate X, Coordinate Y, Width, Height, ScaleX, ScaleY, SkewX, SkewY, SRID, bands count)
  • Get WKB metadata
• [x] ST_RasterFromImage( BLOB, upperLeftX, upperLeftY, scaleX, scaleY, skewX, skewY, srid)
  • Convert image stream into Raster using ImageIO (JAI can extend supported formats)
• [x] ST_ImageFromRaster( RASTER, FormatSuffix )
  • FormatSuffix ex: png tiff
  • ImageIO support also MimeType, but this is less user friendly.
• [x] ImageIO driver for reading WKBRaster as a Raster and/or BufferedImage.
  • Image cannot be read if Blob is freed or connection is closed.
• [x] ImageIO ImageInputStream driver, that create ImageInputStream from JDBC Blob
• [x] ST_MakeEmptyRaster
• [ ] ST_AddBand with offdb image file (delivered with H2GIS)
• [x] ST_BandMetaData(raster rast, integer bandnum=1)
• [x] FILE_WRITE( lob, String ) ??
• [x] Image IO WKB Raster
• [ ] Image IO WKB Raster with offDb bands
• [x] LobDB, RenderedImage wrapping (in order to not break JAI processing chains)

[ebocher]

ST_ImageFromRaster must detect the format suffix no ?

[nicolas-f]

The format of Raster is WKB Raster. This function must translate into another format, defined by the user.

[ebocher]

So this functions is used to convert ?

[nicolas-f]

Yes this is the inverse of ST_RasterFromImage. So you should call something like that:

SELECT ST_ImageFromRaster(ST_RASTERFROMIMAGE(FILE_READ('/home/user/aerial.png'), 150, 200, 1, 1, 0, 0, 4326), 'bmp') bmpData;

[ebocher]

Perfect

[nicolas-f]

Added ImageIO drivers

[nicolas-f]

Added ST_ImageFromRaster

[nicolas-f]

Maybe implement FILE_WRITE( lob, String ), to write image obtained through ImageFromRaster ?

[ebocher]

Yes you are right

[nicolas-f]

Add ST_MakeEmptyRaster

[nicolas-f]

Raster.toString() is converted into human readable metadata: w:10 h:10 bands:3 srid:27572 x:0.00000 y:0.00000 scalex:1.00000 scaley:-1.00000 skewx:0.00000 skewy:0.00000

[gpetit]

@nicolas-f Maybe its more clear to write ST_MakeEmptyRaster ?

[nicolas-f]

ok..

[nicolas-f]

Add ST_BandMetaData

[nicolas-f]

Currently WKB Image parsing is slow because there is absolutely no pixel cache. Here a sample of what is done currently:

I want RGB of pixel 500 red = Blob.getInputStream().skip(adressOfRedBandPixelZero) green = stream.skip(adressOfGreenPixelZero) blue = stream.skip(adressOfBluePixelZero)

I want RGB of Pixel 501 The problem here is the stream is in the blue band area. We have to reopen the stream and skip to the red band for pixel 501.

One solution

The class WKBRasterDataBuffer should cache the bands values for a row. The goal is to reset the minimum of times the stream and reduce the seek amount.

[nicolas-f]

Add ST_WorldToRasterCoord ST_WorldToRasterCoordX ST_WorldToRasterCoordY

[ebocher]

To be consistent with geometry drivers, ST_RasterFromFile function will be renamed by ST_WorldFileImageRead (eg SHPRead) and a new function ST_WorldFileImageWrite will be added.

[ebocher]

Note : I don't want to use raster because it's a type (a category of datatype) and not a format like worldfile, geotiff.

[nicolas-f]

what about ST_RasterFromWorldFile ?

[ebocher]

No because we must also write st_geometryfromfile ;-)

[ebocher]

ST_WorldFileImageWrite will have the following signature

ST_WorldFileImageWrite(RASTER, '/tmp/toto.png')

Usages

SELECT ST_WorldFileImageWrite(the_raster, '/tmp/toto.png') from myRasterTable limit 1;

SELECT ST_WorldFileImageWrite(the_raster,concat( concat( '/tmp/toto_', pkValue), '.png')) from myRasterTable;

[gpetit]

@nico any input about this feature ? We are looking forward using raster in H2GIS ;-)

[ebocher]

Note : The TIFF format will be integrated in JAVA 9 http://openjdk.java.net/jeps/262

[nicolas-f]

Nice.

@gpetit I've merged the raster branch with the last h2 update. I have to write documentation and then create a pull request to h2 database.

[ebocher]

+1 We can help you to write the documentation.

[nicolas-f]

The branch is here https://github.com/nicolas-f/h2database/tree/georaster_patch

Off db raster is still not supported yet. But band metadata can already store the path of the external image.

[ebocher]

Add a unit test ? SELECT FILE_WRITE(ST_IMAGEFROMRASTER(data, 'png'), '/tmp/test.png') FROM test @nicolas-f

[ebocher]

Test done

[ebocher]

A good day https://github.com/h2database/h2database/pull/945