| 16 Jun 2011 05:32 PM |
|
|
Please I am trying to calculate ndvi on landsat TM images using band 3 (red) and 4 (NIR) but no image is being displayed. But is I susbtitute 1 for 4 it does work. Please what is the problem, why cant I use 4?
Thanks
Devolent
|
|
|
|
MariM
Veteran Member
Posts:2396  
| 20 Jun 2011 07:42 AM |
|
|
If you bring up the Cursor Location/Value tool, or run basic stats on the result, are the values actually 0 or are they just very small with perhaps a few outliers? It is likely a data stretching issue if the values are not all 0.
|
|
|
|
Deleted User
New Member
Posts: 
| 20 Jun 2011 01:53 PM |
|
|
Thanks very much for responding.
The cursor location/value tool shows: Scm R:0 G:0 B:0. Data: R:0 G:0 B:0. Is this what you mean data stretching? how do I correct that?
Thanks
Devolent.
|
|
|
|
MariM
Veteran Member
Posts:2396
| 21 Jun 2011 01:14 PM |
|
|
Are you outputting the result to floating point or to byte? If you output to byte, are you changing the min/max? If so, try leaving the min/max at the default values. I believe there is a bug if you change the default values.
|
|
|
|
Deleted User
New Member
Posts:
| 21 Jun 2011 02:05 PM |
|
|
Im outputting to floating. Didnt change the min/max (left them as default).
Thanks,
Devolent
|
|
|
|
MariM
Veteran Member
Posts:2396
| 23 Jun 2011 08:26 AM |
|
|
It is difficult to say what is going on. You might try contacting ITT Technical Support directly. They may need to see your files.
|
|
|
|