Once the AOI is set, take the following steps to choose the image that fits your AOI most:
- Click All Filters and select the Source from the drop-down menu:
- passive sensors (day) -Sentinel-2 L1C, Landsat 8 OLI + TIRS, Landsat 7 ETM +, Landsat 4-5 TM, Landsat 4-5 MSS, CBERS 4 MUX, CBERS 4 WFI, CBERS 4 PAN 10, CBERS 4 PAN5, NAIP.
- passive sensors (night) – Landsat 8 OLI + TIRS, Landsat 7 ETM+, Landsat 4-5 TM.
- passive sensors (low resolution) – MODIS MCD43A4
- active sensors – Sentinel-1 GRD IW, Sentinel-1 GRD EW, Sentinel-1 GRD SM
- terrain Tiles
- high-resolution images – SPOT 5, SPOT 6,7 Pleiades 1A, 1B, KOMPSAT-2, KOMPSAT-3, KOMPSAT 3-A, SuperView, Gaofen 1, Gaofen 2, Ziyuan-3, TripleSat
- EOSDA Storage files – all the files, saved in EOSDA Storage
2. Once the Source, in this case Passive sensors (day) is selected, you can either unclick the satellites you don’t need from the All sensors list, which shows up by default once the Source is chosen, or hover over the necessary satellite, select Only and all the other satellites will be excluded from the list automatically
3. Hover over the satellite image to check if it covers your AOI entirely
4. Check the image details – date, source data, sun elevation, cloudiness, the orbital path number as well as polarisation and shooting mode, in case of radar sensing, in the right side of the image
5. Set the Date or Date period, selecting the start date and the end date
6. Set Сloudiness and Sun Elevation. The cloudiness value (0-100%) is set to 100% by default. The Sun Elevation (0-90°, with min. value=1) is set to 90°
7. Set Polarisation in active sensors dataset
Polarisation can be one of SH (single HH polarisation), SV (single VV polarisation), DH (dual HH+HV polarisation) and DV (dual VV+VH polarisation)
The active sensor images are available in IW (The Interferometric Wide) swath mode – the main acquisition mode over land, which satisfies the majority of service requirements. It acquires data with a 250 km swath at 5 m by 20 m spatial resolution
Using Band Combination tab select specific bands from a multispectral satellite image to create color pictures that are specifically tailored to facilitate the identification of the features of interest. Choose any of the following ways to use it:
- Click the Band combinations icon in the right sidebar, and in Default tab choose the one you need from the list: Natural Color, Color Infrared (vegetation), NDVI, NDWI, SAVI, ARVI, EVI, GCI, SIPI, NBR, Agriculture, False Color (Urban), Land/Water, Healthy vegetation, Vegetation Analysis, Atmospheric Penetration, Index Stack, Shortwave Infrared, Atmospheric Removal, , Snow/Clouds, NDSI, Panchromatic, Thermal, Scene Classification.
- Once a spectral index is applied over the selected territory, you can see a detailed legend, where each color-marked class contains a short description. For example, calculation of NDVI identifies and highlights areas with “dense”, “moderate”, “sparse vegetation”, “open soil” or “no vegetation”.
- In the Custom tab, click New band combination and select either Composite (to visualize different custom band sets) or Single (to visualize one selected band) on the map. Certain band combinations enable to reveal specific features and patterns in the frameworks of the Land analysis
- To create a Composite custom band combination drag the selected band cell and drop it to the appropriate R, G or B cell
- When the combination is set, enter the name in the Untitled band combination field, click empty space and the newly created combination will show up in the list of custom band combinations automatically
- At this step, you can Check, Edit or Remove your custom band combination
- Create the Single band combination, using the same algorithm as for creating the Composite one
- To the Single band combination, you can also apply one of the default color palettes or create a custom one. For this purpose, in the Palette drop-down menu select the one from the list. The palettes are named after the dominant color (or colors) in the palette and arranged in an A-Z order
- Apply the selected palette and view the outcome result on the map
- To create a custom palette, click Create palette icon
- Enter the name in My palette field
- Make all the necessary settings, that is: select Continuous or Descrete (gradient)
- Set the color, using the color picker or set the values in Hex, R, G, B fields
- Set the color hue using the color sliders. Fix the Relative position in %
- Use Delete to remove the color. Once everything is done, select Apply, preview the result on the map and click Save. To discard changes, click Cancel
- Once the palette is saved, it is added on the Custom Palettes list automatically
- Create and customize index, using the following options: enter the index formula in the Input your formula field. Apply the default or custom color palette
- To customize the color Legend, apply Inversion, set the Levels (the legend borders) and the number of Classes (gradient palette)
- Once all the settings are applied, you can save and download the output file or each band separately. To download the band combination, go to the Custom tab, select the necessary one and click the download button on the right
In the Visual tab select Resolution, Format and use Crop by extent option, if necessary
To Download band combinations as one file choose and convert selected bands (BO8, BO4) to GeoTIFF, crop by visible extent on the map. Bands with the same resolution are merged by default, but if you don’t need it, clear the tick box
To Download band combinations separately, go to Analytic tab, hover over the selected band and click downloading icon in the band field.
Index change notification manager
EOSDA LandViewer launches a new important feature that addresses the needs of every user – the index change notifier. It allows tracking the smallest change in the index values of your AOI. The process is as follows: it scans new satellite images of your AOI, detects changes in the index values, and sends urgent e-mail notifications to the end user.
To get the index change notifications, take several simple steps:
1. Save your AOI
2. Check whether your AOI is successfully added on My AOI list
3. Add it to “Notification manager”
4. Choose the sensor, the index, and subscribe for email notifications
5. Once your AOI has been added to Notification Manager, click Open to check or modify the setting if necessary
6. Check the details, Add new AOI or modify the notification settings if necessary
Once all the settings are made, you will receive an email notification each time the index is changed
Contrast Streching function enables to improve the contrast in an image by stretching the histogram values. The method is based on cutting off the upper 2% and the lower 2% values of the cumulative curve. The default values 2% and 98% make the darkest two percent of the pixels black and the brightest two percent of the pixels white, which throws out a lot of data. Contrast Stretching works on layers of RGB and Grayscale images. EOSDA LandViewer offers the following contrats stretching options:
To set and customise the contrast settings of the selected satellite image. For this purpose take the following steps:
- select the Contrast Stretching from the tool-box on your right to check the values set by default
- use Edit to alter the default values or set the custom ones in R, G, B fields
- Click Save, then Apply. To discard changes click Cancel
You can also apply one of the available contrast stretching options, that is:
Local histogram stretch
It is the raster image contrast-enhancing technique. The approach is based on stretching the range of intensity values it contains to span a desired range of values. The stretching is performed within the local area of the pixel values range the image contains
Stretch histogram to full dataset
Full contrast stretch – is the contrast-enhancing technique, based on the stretching the range of intensity values the image contains. The stretching is performed within the entire area of the pixel values range
Local cumulative cut stretch, 2-98%
It is the raster image contrast-enhancing technique. It’s based on stretching the range of intensity values it contains to span a range of values from 2 to 98%. The stretching is performed within the local area of the pixel values range the image contains where the values from 0 to 2% and from 98% to 100% are cut off.
Cumulative cut stretch, 2-98% (default)
It is the raster image contrast-enhancing technique. It’s based on stretching the range of intensity values it contains to span a range of values from 2 to 98%. The stretching is performed within the entire area of the pixel values range the image contains where the values from 0 to 2% and from 98% to 100% are cut off.
- choose Advanced Settings and customise Extent and Cumulative count cut in the drop-down menu. Сlear a tick box and cancel Cloud correction and Antialiasing, if needed. Once all the settings are set, click Apply to save changes.
Time Lapse animation
Time Lapse animation – is a video made from several single images dated from the different periods of time so that you can visualize, view and detect the changes.
To create a Time Lapse video, select your AOI, apply necessary satellite filters and click Time Lapse animation icon on the right. Then set the time period (start and end date) you need and select the images to compare using “+”.
Once the images are selected, click Create Time Lapse box in the bottom right of the screen.
At this step, you can set the band combination from the list available by default – Natural Color, Color Infrared (vegetation), NDVI, NDWI, SAVI, ARVI, EVI, GCI, SIPI, NBR, Agriculture, False Color (Urban), Land/Water, Healthy vegetation, Vegetation Analysis, Atmospheric Penetration, Index Stack, Shortwave Infrared, Atmospheric Removal, Snow/Clouds, NDSI, Panchromatic, Thermal.
Once the appropriate index is selected, you can apply the custom settings – sort images by date (ascending/descending), set quantity of frames per second, resize the video, create a gif, show dates as well as download and share the video.