عدة اسئلة في جمع النطاقات فى برنامج Envi

[نجد جمال]

is vegetation index NDVI?
NDVI
Normalized Difference Vegetation Index; a vegetation index used to transform multispectral data into a single image band whose values indicate the amount of green vegetation present in the pixel. ENVI uses the standard NDVI algorithm, where NIR is a near-infrared band:


IF YES

From the ENVI main menu bar, select Transform NDVI. The Input File dialog appears.
Select an input file and perform optional Spatial Subsetting, then click OK. The NDVI Calculation Parameters dialog appears.

Specify the Input File Type (TM, MSS, AVHRR, and so on) from the drop-down list. ENVI automatically enters the bands it uses to calculate the NDVI in the Red and Near IR fields.

To calculate the NDVI for a sensor type not listed in the drop-down list, enter the band numbers in the Red and Near IR fields.

Select output to File or Memory.

Select one of the following output types from the Output Data Type drop-down list.
Byte: Enter the Min and Max NDVI value in the fields supplied.

Floating Point

Click OK. ENVI adds the resulting output to the Available Bands List.