NoData not really NoData?

Discussion created by rogier83 on Feb 2, 2011
Latest reply on Jun 9, 2016 by awagtendonk

In ArcMap 9.3, I have multiple raster datasets which apparently have NoData pixels (that's what Identify shows). But the cells do not behave like NoData, e.g.

* the NoData color doesn't work, instead the pixel has the 'lowest' color in the color range;
* checking for NoData values using Con(IsNull([in_grid])) yields only 0, so no pixels are recognized as NoData
* when applying a focal mean function (3x3), all 9 pixels get the same "NoData" characteristics as mentioned above, although the other 8 pixels do have (floating point) values.

What might be the problem and how can I filter/replace these "NoData" pixels?

Best regards,
Rogier de Jong