This guide provides a step-by-step approach to assess coastal sand loss due to Cyclone Jasper using drone data. Learn how to visualise and compare datasets from different time periods, identify areas of significant erosion, and utilis AI tools for precise mapping. By following the instructions, you will be able to effectively estimate the extent of sand loss, making it a valuable resource for environmental analysis and coastal management.
Creating a project
1. Navigate to https://data.geonadir.com/myprojects
Projects are where you’ll organise all related datasets and results in GeoNadir.
2. Click "New project"
3. Click on the project name "Untitled"
4. And change to "Trinity Park erosion example [[Enter]]"
Using existing drone data
GeoNadir hosts thousands of drone mapping datasets from all around the world. Many people have uploaded their data as FAIR - findable, accessible, interoperable, and reusable. This means that we can use them in our project!
The datasets we’ll use here were captured at Trinity Park, near Cairns, in Queensland Australia before and after Cyclone Jasper.
5. Click the "Add data icon" and "Search existing drone data"
6. Click the "Search" field.
7. Type "trinity park [[Enter]]"
8. Select the datasets for Dec 2023 and Jan 2024. Click "Add to project"
Note that the date the data were captured is listed on the top right hand side of each dataset 'card' (i.e. Jan 02, 24; Dec 11, 23) and is not always in the name.
Exploring the data
9. Hover over the January dataset and toggle its visibility on and off.
What differences can you see between the datasets? Can you see the areas of significant erosion?
Pay attention to the beach width and vegetation edge. These are indicators of erosion.
What differences can you see between the datasets? Can you see the areas of significant erosion?
10. Click "Trinity Park, Jan 2024" to select this layer
Notice that when a layer or combination of layers are selected, new tools appear along the top menu bar.
11. Click the tool to compare layers (or use the keyboard shortcut \).
12. Use your cursor to swipe between layers and investigate the extent of erosion.
The vertical bar lets you swipe between time periods / layers for a direct visual comparison.
13. Use the "Esc" key to disable the compare tool
Estimating sand loss
14. Click the down arrow next to the map style icon to expand options
15. Remove the basemap by selecting "Clear".
This is not a critical step, but helps to reduce distractions so that you can focus on the drone mapping data.
16. Once again, select the "Trinity Park, Jan 2024" dataset
17. Hover over 'Orthomosaic' to view the opacity slider
18. Decrease the opacity of the 2024 dataset so that you can visualise the 2023 data below it at the same time.
You will need to have a Professional or Pro + subscription to GeoNadir to complete the following steps. Contact us for a free trial!
Alternatively you can use the drawing tools on the top toolbar to manually trace the area of sand loss.
Now we are going to use some AI to map the changed area.
19. Open the "Magic Wand" tool
The Magic Wand uses colour and texture similarity to automatically detect the feature you sample.
20. Left click in the area where the 2023 sand is visible underneath the 2024 data to create a 'sample' for the AI to use.
21. Click four or five more times to build up your samples. There's no 'exact' number to use.
22. Click "Preview"
23. If the model has adequately found the bounds of your eroded area, click "Save" (or press "Enter"). If some parts have been missed, create a few more samples by left clicking on the map.
If it has given you an area larger than required, you can hold shift and click in areas that you don't want included.
Changing your zoom level will impact the magic wand results, so experiment with zooming in and out.
A smaller zoom window focuses the model on finer detail, while zooming out generalises to broader regions.
24. Once saved, the polygon will appear in your Table of Contents. Click it's icon to change its style.
25. In the style bar, change the fill and stroke outline if you wish.
What is the area of sand lost? Hint - have a look in the Table of Contents.
This area value gives you a direct estimate of sand lost. You can record it for comparison with other sites or future surveys.
How might this workflow help coastal managers plan resilience strategies?