QGIS Plugin Menu 1 – Mapping setup
QGIS Plugin menu 2 – Upload to NAFI.
THIS SECTION NEEDS TO BE UPDATED
- DRW_dMIRB_T12 – DRW (Darwin Region) dMIRB (difference middle infrared burn ratio) T12 (Time 1 – Time2)
- DRW_dMIRB_T13 – DRW (Darwin Region) dMIRB (difference middle infrared burn ratio) T12 (Time 1 – Time3)
- DRW_NATURAL_COLOURS – T1 (Tile one) DRW (Darwin Region) Natural_Colours
The layer names now included timepoint (a.k.a. sentinel-2 satellite overpass) date in the format YYYYMMDD. Timepoints are ordered by decreasing dates, T1=9 May 2021, T2= 4 May 2021 ….
DRW_NATURAL_COLOURS can be used as a base map. This is the latest overpass.
So DRW_dMIRB_T12 shows the burnt areas between the previous week (overpass) and the latest overpass. Burnt areas are clearly highlighted in red.
DRW_dMIRB_T13 shows the burnt areas between the week before last and the current week. These two time periods are used to reduce the impact of cloud that may obscure part of an image during and overpass. In the image below
where, the first date string is the T1 overpass date, and the second date string is the T2 overpass date.
- The files ending seg_150 contains polygons for just the main burnt areas. This is the main file you will use.
- The files ending seg_100 contains polygons for all burnt areas including some burnt areas that maybe less clear. This file is also more likely to contain many more polygons that are not fire at all.
- The files ending seg_250.shp contain less polygons.
To load the polygons into QGIS just double click them from the QGIS browser window.
Make the infill of the polygon transparent by:
- Double clicking on the auto-map polygon layer to open the payproperties window. Make sure you have the ‘Symbology’ window seltected.
- Click on ‘Simple Fill’
- set the Fill Style to ‘No Brush’. The click ok
5. Create a new polygon shapefile
Now you need to create a new polygon shapefile that you will copy your mapped fire layers into. In the top menu select the Layer menu then ‘Create Layer’ and finally ‘New Shapefile Layer’ as shown below.
Save your new shapefile in a working directory on your computer. Make a directory that you use for all your fire mapping. Give the shapefile and the folder you save it in a name following the following naming convention.
Start with ‘FSDWN’ (this stands for fire scars Darwin) then the mapping period from the first image date to the second image date. For example FSDWN_20210419-20210423. This allows others to know where and when the mapping was conducted.
6. Copy burnt areas from the auto-segments to the new burnt area mapping shape file.
Now make the new file editable by clicking the edit (pencil) button.
Now activate the selection tool and use the cursor to draw a box around some polygons covering a burnt area to select them
When selected they will appear yellow.
Now copy the selected features either through the edit menu item or using ctrl+c.
The copied polygons should now appear in the final mapping layer you created.
Continue selecting, copying and pasting all the burnt areas you can identify into the final map shape file. It is good partice to save your edits as you work and when you have finished.
There is a short-cut for simplifying the cut and paste process using a python script within QGIS. Learn how to use to implement this shortcut here.
Once you have finished the mapping the next step is to give the mapping layer some identifing information and upload it to NAFI. This is explained in the next section.