I would like to calculate NDVI and EVI from ladsat 5 data. The data
is scaled 0-255. Do I need to convert this to watts/meter sqaured
before I proceed? I have done this calculation
(band4-band3)/(band5+band3) and get a map filled with zeros. What am
I doing wrong.
--
Stephen Sefick
Let's not spend our time and resources thinking about things that are
so little or so large that all they really do for us is puff us up and
make us feel like gods. We are mammals, and have not exhausted the
annoying little problems of being mammals.
I would like to calculate NDVI and
EVI from ladsat 5 data. The data
is scaled 0-255. Do I need to convert this to
watts/meter sqaured
before I proceed? I have done this calculation
(band4-band3)/(band5+band3) and get a map filled with
zeros. What am I doing wrong.
maybe it is integer division resulting in a integer result?
try (1.0*band4-band3)/(band5+band3) to introduce a floating
point value and so get a floating point result.
As I looked into it a little bit more. It was more complicated than I
had previously realized, so my solution was to write a series of
scripts to convert Digital Number to radiance -> TOP of Atmosphere
reflectance -> NDVI. If anyone is interested in the scripts please
don't hessitate to ask for them.
Stephen Sefick
On Mon, Sep 21, 2009 at 3:05 PM, Hamish <hamish_b@yahoo.com> wrote:
stephen sefick wrote:
I would like to calculate NDVI and
EVI from ladsat 5 data. The data
is scaled 0-255. Do I need to convert this to
watts/meter sqaured
before I proceed? I have done this calculation
(band4-band3)/(band5+band3) and get a map filled with
zeros. What am I doing wrong.
maybe it is integer division resulting in a integer result?
try (1.0*band4-band3)/(band5+band3) to introduce a floating
point value and so get a floating point result.
Hamish
--
Stephen Sefick
Let's not spend our time and resources thinking about things that are
so little or so large that all they really do for us is puff us up and
make us feel like gods. We are mammals, and have not exhausted the
annoying little problems of being mammals.