[GRASS-user] NDVI from landsat 5 TM

[stephen sefick]

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 at 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.

								-K. Mullis