<div>Hello,<br></div><div>I'm a GIS student and in my project I need to generate vegetation indexes. I've generated it succesfully yesterday using both python2.7 and grass gui .I'm using WinGRASS-6.5.svn-r54428-453 on Win7. Today -I don't know why- grass started to generate 1 pixel NDVI map. The formula is as simple as it could be: float(b4-b3)/(b4+b3) as most of you already know. My data is not corrupted, I'd saved original maps somewhere else and it was my first check that whether there is a corruption. Also using QGis 1.8.1 I can generate correct NDVI map with same data. You can check it here:</div>
<div><br></div><div><a href="http://r.info">r.info</a> map=ndvi4@PERMANENT                                                      <br> +----------------------------------------------------------------------------+<br> | Layer:    ndvi4@PERMANENT                Date: Tue Jan 01 04:06:35 2013    |<br>
 | Mapset:   PERMANENT                      Login of Creator: murat           |<br> | Location: newLocation                                                      |<br> | DataBase: D:\gis\grassWS                                                   |<br>
 | Title:     ( ndvi4 )                                                       |<br> | Timestamp: none                                                            |<br> |----------------------------------------------------------------------------|<br>
 |                                                                            |<br> |   Type of Map:  raster               Number of Categories: 255             |<br> |   Data Type:    FCELL                                                      |<br>
 |   Rows:         1                                                          |<br> |   Columns:      1                                                          |<br> |   Total Cells:  1                                                          |<br>
 |        Projection: UTM (zone 36)                                           |<br> |            N:          1    S:          0   Res:     1                     |<br> |            E:          1    W:          0   Res:     1                     |<br>
 |   Range of data:    min = nan  max = nan                                   |<br> |                                                                            |<br> |   Data Description:                                                        |<br>
 |    generated by r.mapcalc                                                  |<br> |                                                                            |<br> |   Comments:                                                                |<br>
 |    float(L71175034_03420050627_B40@PERMANENT -                             |<br> |    L71175034_03420050627_B30@PERMANENT) /                                  |<br> |    (L71175034_03420050627_B40@PERMANENT +                                  |<br>
 |    L71175034_03420050627_B30@PERMANENT)                                    |<br> |                                                                            |<br> +----------------------------------------------------------------------------+<br>
(Tue Jan 01 04:06:51 2013) Command finished (0 sec)                             <br></div><div><br></div><div>I uninstalled 
WinGRASS-6.5.svn-r54428-453
 and installed WinGRASS-7.0.svn-r54453-453, I've deleted mapset and location and the recrated them also. I couldn't think anything else please give me some information.</div>