AgLeader's SMS Advanced can leverage DroneDeploy imagery as both a visual reference and as a true data product; suitable for NDVI analysis.
Download Othomosiac from DroneDeploy
- Select the Map you wish to import from the DroneDeploy dashboard
- Choose 2D Map as your map type, and then Export the map.
Note:
Even if your goal is NDVI analysis, SMS uses the original ortho for the calculations!- Enter an email address to receive the exported map. As SMS can easily get bogged down with high resolution imagery, consider starting with an export Resolution of 50 cm/px initially. If you find that more detail is needed, try 20cm/px, and so on. An export at 50cm resolution is still less than 20 inches per pixel; which is more than sufficient detail for most farm applications and NDVI analysis. For the Projection, WGS84 offers the widest compatibility. Select Single Image to deliver the map as one cohesive mosaic. Finally, click Export to submit your request. Depending on the mosaic size and image quality, image export may take a bit (Care for a coffee break, anyone?)
- Upon receipt of your exported mosaic in your emaIl inbox, click the download link to procure a zipfile containing your mosaic. When prompted, save the zipfile to your computer.
- Upon notification in your browser that the download is complete, locate the downloaded orthomosaic on your computer (in the Chrome browser, you’re looking for Show in Folder on the drop-down on the file link off the downloads bar).
- Using the file extraction method of your choice, extract the orthomosaic from the zipfile.
Note:
Most modern operating systems have native extraction tools.
With the imagery extracted, it’s time to open SMS. At this point, you’ll need to decide how you’ll be using the imagery.
To use imagery as a background image:
- Open SMS. If prompted, Open an Existing Project.
- From the menubar, select Read File(s).
- Next, select Import a File from a Generic Source, and click Start Importing Generic Files.
- On the “Select File Import Method” dialogue, choose Images, and then Select File(s) to Import...
- Navigate to the location where the image was saved and Open the image.
- Choose any optional clipping / cropping settings, and choose Next. For this example, we’ll import the entire image.
Note:
**Clip by Manual Selection(s)** is good to remove the empty space on the edges of the orthomosaic- In this instance we’re importing a standard true color or “RGB” image; so select Import Image as is and click Next.
- Because we want to view the image in reference to other data, we’ll want to Add as a Possible Map Background. Be sure to give your background a Description that will be helpful later on (date, field name, etc). Click Finish to complete the import (this may take a little while if you’re importing higher-resolution imagery).
- We’ll now need to add our imported map background to a map. Navigate the Management Tree in your project workspace to either Create New Map from existing data (like shapefiles) or go to an existing open map tab.
- From the Map toolbar, select Set Background. If the Set Background dialogue appears, select Add Background.
- Use the Check the Background Maps to be Added dialogue to select your imported ortho imagery and click Add.
- With the new background ortho image added and selected, click OK.
- Depending on the other layers you may be displaying, it may be necessary to toggle off other layers by editing the legend or adjust transparencies. These actions are performed using the Edit Legend dialogue and the Transparency slider respectively.
To use imagery as a map layer for NDVI analysis:
- Open SMS. If prompted, Open an Existing Project.
- From the menubar, select Read File(s).
- Next, select Import a File from a Generic Source, and click Start Importing Generic Files.
- On the “Select File Import Method” dialogue, choose Images, and then Select File(s) to Import...
- Navigate to the location where the image was saved and Open the image.
- Choose any optional clipping / cropping settings, and choose Next. For this example, we’ll Clip by Manual Selection(s) to remove the empty space on the edges of the orthomosaic.
- To clip, define your region using the Select Rectangle tool on the top left of the vertical toolbar. Click once on the image to begin defining the region, and click again on the opposite end of the field to finish. Click Next to commit the clip.
- Unlike a “true color” or RGB image, band assignment is important for NIR imagery. Knowing your camera specification is key! For this mission, we flew a Canon s100 where the red was modified to receive near-infrared. So, we’ll define band setting specific to the camera. Select Create New Datasets from Image Color Bands, and from the dropdown select New 3-Band Image Dataset. For the purposes of representation, Assign Red to band 1, Green to Band 2, and Blue to band 3. You can either leave the Generate Name checked, or uncheck it and assign your own name. Finally, click Add to lock-in your band selection as a new dataset and click Next.
- As opposed to using the image as a background for reference, we’ll want to make some management decisions from our NDVI. To make that happen, you’ll want to instead Add to Management Hierarchy and click Finish to complete the import.
- Once imported, you’ll need to decide which portion of the management tree the image belongs in. Select the appropriate Grower, Farm, Field, Year, and Product applicable to your management workflow and click Accept.
- Once added to the Management Tree in the Project Workspace, you’ll want to select the image and Create [a] New Map in which to perform the NDVI analysis.
- With the new image added to a new map, it’s time to run the Analysis Wizard.
- In the Select Analysis Type to Run dialogue, choose NDVI Analysis for a Single Field.
- For this demonstration, we’ll leave parameters in the Select Data Filters dialogue at defaults. Click Next.
- For the NDVI Settings dialogue, we’ll be setting the grid size that SMS uses to assign NDVI values to each pixel. Selecting Use Image Res will yield most accurate results but take significant processing time (minutes instead of seconds). If processing time is a concern, consider using a value under Manual Grid Size equivalent to two or even four times that of image resolution
A word on resolution...
It is *NOT* recommended to **Use Image Res** if your orthomosaic was exported at anything other than 50cm!- Under Select Color Bands for Processing, you’ll need to know how your camera was put together to assign appropriate bands. For our MaxMax-modified s100 in this example, we know that Red equates to the Near Infrared Band and Green equates to the Visible Red Band. Click Finish to begin analysis.
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After processing, You’ll be presented with an Analysis Editor where you’ll have the ability to select a subset of the NDVI analysis. As that goes a bit beyond the scope of this tutorial, simply Save the default analysis so it can be viewed on the map.
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On the new map, your analysis will show as one color until the correct attribute representation is selected. Use the Attribute drop-down in the Map Layers pane to select NDVI.
