What are the range of NDVI values for Urban, River, grass land, agricultural land, forest (dense and less dense) and others if you know?
If I have a NDVI of range -0.14 to 0.59, how can I classify them ?
I used raster calculator to calculate NDVI value,
NDVI = float(band 5(IR) - band 4(Red))/float(band 5 + band 4)
Source was Landsat 8.
Hello Mohima. As far as I know, NDVI values smaller than 0.1 correspond to areas without any vegetation, like rocks, sand, water bodies or snow. From 0.1 to 0.2 you have almost no vegetation. Spare vegetation like senescing crops, shrubs and also some types of grassland have moderate NDVI values from approximately 0.2 to 0.5. High NDVI values (higher than 0.6) indicate dense vegetation structures, like forests or crops at their peak growth rate.
Although, I do not understand why you have values below -1. As far as I know, NDVI values range from -1 to +1.
Cheers Paul
Agricutlure NDVI values are between 0.6 and 0.7 ..or higher than 0.6.
http://precisionagricultu.re/ndvi-in-agriculture/
Healthy plants absorb most of the visible light while reflecting a large amount of the near-infrared light. Unhealthy plants do the opposite. NDVI is an extremely helpful tool to assess plant health, and understanding it is important.
high values indicate temperate and tropical rain forests (1.4 to 0.59).
In general, NDVI values range from -1 to +1. Since you have a value of 1.4, you might be using a different scale, so the general classification values (i.e. negative values= water, ~0-0.3 bare land/built-up areas, 0.3-0.6 moderate vegetation cover and >0.6 dense vegetation) might not be valid in your case.
Regarding agriculture, the NDVI values can always change, based on different reasons such as stage in the cropping cycle, plant health and crop type.
Thank you Indishe Senanayake , Sorry it was typing mistake, -0.14 was the value. I used the formula- float(band 5 - band 4)/float(band 5 + band 4). As I got the highest value 0.59, now I have to identify the crop status before classifying? Can you please share the different values for different crop type, if you know? Are agricultural lands considered as dense vegetation?
Thank you, Luis Ernesto Cervera-Gomez, I was looking for this chart.
Thanks Paul Griesberger, Sorry I mistyped the value. The range was -0.14 to 0.59. As Crops considered as dense vegetation at their peak growth. So my highest value(0.59) indicates that crops may be newly planted?
Hello Mohima, you have to look at the NDVI values for each field separetly. If the NDVI value for a specific field is 0.59, I would guess that the crops are neither newly planted nor at their peak growth rate, but somewhere in between.
Cheers Paul
The value range of an NDVI is -1 to 1. Negative values of NDVI (values approaching -1) correspond to water. Values close to zero (-0.1 to 0.1) generally correspond to barren areas of rock, sand, or snow
In most cases, NDVI values between 0.2 and 0.4 correspond to areas with sparse vegetation; moderate vegetation tends to vary between 0.4 and 0.6; anything above 0.6 indicates the highest possible density of green leaves
Mohima Sultana Mimi Hi Mohima,
These are the answers to your questions:
I used the formula- float(band 5 - band 4)/float(band 5 + band 4). As I got the highest value 0.59, now I have to identify the crop status before classifying?
- The formula you used is correct for Landsat 8, but not other Landsat imagery since their band numbers are different.
Can you please share the different values for different crop type, if you know?
-Classifying crop types based on NDVI is difficult, since NDVI values are affected by many factors, such as (growth cycle of crop, climate, soil type, spacing between plant rows, agricultural management practices, signals from mixed pixels in such as in rice farming, etc.). Furthermore, NDVI is affected by solar illumination angle. This leads towards the development of EVI. However, with a time series of your study area, you can try to define NDVI range unique to your crops.
Are agricultural lands considered as dense vegetation?
- Depends on the crop type. NDVI is a measurement of greenness (chlorophyll). A plantation with large canopy cover (e.g. mango), can be fallen into the dense-cover NDVI range based on the plant health, spacing between trees, etc.
Indishe Senanayake , thanks for the answers. Now I have a better understanding.
Between 0.2 and 0.4 for sparse vegetation, 0.4 to 0.6 for moderate vegetation and above 0.6 indicates the highest possible density of green leaves.
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