[GRASS5] 0 != no data

[Glynn Clements]

Justin Hickey wrote:

> Unfortunately, I have no idea how to fix this problem. The ideal
> solution is to find the code that interprets 0 as "no data" and
> eliminate it. However, I don't even know how to search for this type of
> code. Does anyone have any ideas on how to solve this?

Until recently, the most likely reason would have been the use of
G_put_map_row(), which treats zero as null unless G_zeros_r_nulls(0)
is called first.

However, Markus recently replaced all of uses of this function with
G_put_raster_row() (or similar), which doesn't treat zero as null.

There is one reference to G_put_map_row_random() in
src/imagery/i.ortho.photo/photo.rectify/write.c; this function also
uses the zeros_r_nulls setting. Are you using i.ortho.photo?

Apart from that, something would have to be explicitly setting zero
cells to null using G__put_null_value_row() (or even lower level
functions).

-- 
Glynn Clements <glynn.clements at virgin.net>