Alteia provides a wide range of basic to advanced scouting maps for crop monitoring and analysis. It is also possible to generates custom scouting maps.
This tutorial provided details about scouting maps and explains how analyze the maps.
1. Available Maps
Basic Scouting Maps
DESIGNATION DESCRIPTION FORMULA RGB Bird View Bird View Composition: red, green, blue NDVI Normalized Difference Vegetation Index Crop Vigor: Map to analyse vigor, that is mix of biomass development and crop health. The basic tool to scout for field anomalies. NDVI = (nir-red)/(nir+red) NDRE Normalized Difference Red Edge Chlorophyll Content: Map to analyse chlorophyll content, thanks to an index that correlates well with chlorophyll. The basic tool for nitrogen recommendation based on chlorophyll analysis. NDRE = (nir-red_edge)/(nir+red_edge) VARI Visible Atmospherically Resistant Index Greenness: Map to discriminate green plants from the remaining, soil as an example. VARI = (green-red)/(green+red-blue) MCARI2 Modified Chlorophyll Absorption Index Ratio 2 Green Biomass: Map that is a good predictor of green leaf area index to analyse biomass development. MCARI2 = 1.5*(((2.5*(nir-red))-1.3*(nir-green))/sqrt(((2*nir+1)^2)-(6*nir-5*sqrt(red))-0.5)) PRI Photochemical Reflectance Index Map that values spectral bands where photosynthetic pigments might be affected by water stress conditions such as chlorophyll and carotenoids. PRI = (green_b531-green) / (green_b531+green)
Advanced Scouting Maps
DESIGNATION DESCRIPTION FORMULA MSAVI2 Modified Soil-Adjusted Vegetation Index 2 Soil-Ajusted Crop Vigor: Map to analyse crop vigor, that is mix of biomass development and crop health to scout for field anomalies. Main difference with NDVI is that it removes partly the effect of soils. Thus, this index is more suitable to use at early stage of crop development or where canopy is not closed. This is an MSAVI2 map, that is a combination of red and NIR infrared.
MSAVI2 = (2*nir+1-sqrt(((2*nir+1)^2)-8*(nir-red)))/2
CIR Colored Infra-Red False color photograph that highlights vegetation. Composition: nir, red, green CCCI Canopy Chlorophyll Content Index Map that is correlated to N Status / Chlorophyll concentration and can be valued to benchmark chlorophyll status or feed nitrogen variable rate maps.
CCCI = (nir+red)*(nir-red_edge)/((nir-red)*(nir+red_edge))
2. Required Inputs
Following chart shows which sensor bands are used from the multispectral camera to calculate scouting maps. Please note that for Bird View, eith er a RGB sensor or separate R,G,B bands, may be used:
3. Output File Formats
All maps listed above are output as rasters, in .tif file format.
4. How to generate Scouting Maps ?
There are different ways to generate scouting maps in the Alteia Platform:
- Within the Photogrammetry process: in the settings of the photogrammetry it is possible to select basic and advanced scouting maps that will be generated within the process (for multispectral only).
- With the Generic Scouting map analytic that allows to generates basic and advanced scouting maps from an orthomosaic (multispectral or RGB)
- With the Custom Scouting Maps analytic that allows to generate custom scouting map from an orthomosaic (multispectral or RGB) and based on a specific formula.
5. Exploring Maps
Open your site, and from the left panel, go to the BASE LAYERS section. You can rearrange this layer organization if needed (read Browsing and Arranging Layers).
6. Analyzing Maps
If you click on the map, an information panel appears on the right side with different tools to analyze the map.
Value at point
This tool allows to check agriculture indice value at any point of the scouting map:
Scouting Map Value Distribution
Read the value distribution in a scouting map from the information panel, under STYLE section. Value distributions can be displayed with these modes:
|Mean and standard deviation||Values are centered on the mean with 1 standard deviation discarded at each extremity|
|Absolute||All values are displayed.|
|Cumulative % cut||Lower and upper values are discarded. You can set the % of value to discard (default is +/- 3%).|
|Custom||Select the range on which you want to display the map:
The color chart options are:
- Green-Yellow-Red (i.e. lower values are in green)
Data Extraction from a point annotation
Draw a point annotation and press Extract data from point information panel. All available indices values at point will be displayed:
7. Exporting Scouting Maps & Statistics
All generated Maps and Statistics can be exported from the Downloads section. Maps are available under .tif format.
8. Details about Basic Scouting Maps
RGB (Bird View)
To view the orthomosaic, enable RGB from the BASE LAYERS section in Analytics left panel :
NDVI (Normalized Difference Vegetation Index)
NDVI gives indication of the photosynthetic activity, crop vigor and helps spot anomalies.
- NDVI of dense vegetation canopy will tend to positive values (0.3 to 0.8).
- Soils generally exhibit a near-infrared spectral reflectance somewhat larger than the red, and thus tend to also generate rather small
positive NDVI values (0.1 to 0.2).
- Moderate values represent shrub and grassland (0.2 to 0.3)
- High values indicate temperate and tropical rainforests (0.6 to 0.8)
NDRE (Normalized Difference Red Edge)
NDRE is used to assess field chlorophyll content, and thus nitrogen content or stress detection (at the earliest stage possible, before NDVI).
- Soil typically has the lowest values
- Unhealthy plants have intermediate values
- Healthy plants have the highest values
VARI (Visible Atmospherically Resistant Index)
VARI serves to isolate soil from plant. Usually utilized if RGB sensor only, less accurate than NDRE or NDVI.
MCARI2 (Modified Chlorophyll Absorption Ratio Index 2)
MCARI2 is employed for Green biomass evaluation.
PRI (Photochemical Reflectance Index)
PRI serves to identify areas of the field suffering from water stress, evident by clusters of pigments (such as chlorophyll and carotenoids).
9. Details about Advanced Scouting Maps
MSAVI2 (Modified Soil-Adjusted Vegetation Index 2)
MSAVI2 is for use with early stage crops or where the canopy is not closed to help analyze crop vigor and identify anomalies (similar to NDVI, this excludes soil).
CIR (Colored Infra-Red)
CIR serves to isolate vegetation from the surrounding environment.
CCCI (Canopy Chlorophyll Content Index)
CCCI serves for Chlorophyll concentration evaluation, to correlate nitrogen and chlorophyll concentration responses or feed nitrogen variable rate maps.