tRNS flag not working in latest version

[olcl@…]

In previous versions of rasdaman and petascope it was possible to set a tRNS flag to set that colour to be transparent, like the query below :

for c in (CCI_chla_monthly)
return
encode ( (char)

((c[t(3)] ≥ 0.0) * c[t(3)] ) * 255, "png", "tRNS=0x00;0x00;0x00")

This query now does not return an image with any transparency as can be seen in the images attached.

[olcl@…]

file showing old transparency ability

[olcl@…]

image showing no transparency

[Dimitar Misev]

GDAL should set the NODATA value to be transparent in PNG, but I'm not sure if you can pass the NODATA value.

Can you try maybe

 for c in (CCI_chla_monthly)
return
encode ( (char)

((c[t(3)] >= 0.0) * c[t(3)] ) * 255, "png", "NODATA=0")

[olcl@…]

Setting the NODATA flag does not cause any errors with the latest petascope but does not produce an image with transparency either.

[olcl@…]

this ticket is mirrored on the earthserver trac @ ​http://212.201.49.163/trac/ticket/92

[Dimitar Misev]

I submitted a patch that will allow to recognize the nodata parameter. Details about the parameter at the encode function page.

[Dimitar Misev]

Alternative JSON output encoding:

$ rasql -q 'select info(c) from mr as c' --out string
rasql: rasdaman query tool v1.0, rasdaman v8.3.1-g8897c51 -- generated on 07.12.2012 16:06:36.
opening database RASBASE at localhost:7001...ok
Executing retrieval query...ok
Query result collection has 4 element(s):
  Result object 1: {
 "oid": "150529",
 "baseType": "marray <char>",
 "tileNo": "1",
 "totalSize": "54016B",
 "tiling": {
	"tilingScheme": "no_tiling",
	"tileSize": "2097152",
	"tileConfiguration": "[0:511,0:511]"
 },
 "index": {
	"type": "rpt_index",
	"indexSize": "0",
	"PCTmax": "4096B",
	"PCTmin": "2048B"
 }
}

[Dimitar Misev]

ups, wrong ticket.

[Dimitar Misev]

Fixed in changeset:299a268

As explained here please use the nodata parameter.