# QGIS: Calculate NDVI for the Drone Geotiff File

Sometimes you need to calculate the average NDVI for some polygon inside the field. You can do the following in a QGIS program.<br>

<figure><img src="https://lh4.googleusercontent.com/fkankewAK-NkgRxklkXsY_17vIFeDwTjuCNNPvHPX2yzdAQsAx3sWvbQpSnnB8AxG85zYHEyNreHFAUnuD1SzaOZ5gkw-6JZ4X1xAkLs_f7ZNqGogyXOfABMxIBg4LQiO1yg_-OX4J5FtUoQlmPtAw" alt=""><figcaption></figcaption></figure>

#### 1 - Visualize Initial Drone NDVI geotiff

<figure><img src="https://lh6.googleusercontent.com/TnFIzVA_U7L1Z4oMmnOAKZHZQBQ7-1-IqrPAidFzzh7SSF-9KWLAf5xDdwpifj3Ff847fN-wS2tU6jzWcm4qUa4dNkbX287BNpakmOHDqGvsrBPiCkICYpxN_qJiJ2EBkKcJjauq02KAAAyKLB7Gbg" alt=""><figcaption></figcaption></figure>

#### 2 - Create a new layer

<figure><img src="https://lh6.googleusercontent.com/XjSDzTuLAggVtP0SizpQMRjG6jBsUQVS2MKFxbauRFUD_YOq2KsbXo6Ov3sTiO2r158q9qyXGQyiSiC3IbMrx-SboOrVfEs5bvgYoVIXcqyIQfffKeoKdCDRhQDkx65xaPTpKRrBhuTJDXPJlpQfZA" alt=""><figcaption></figcaption></figure>

#### 3 - Setup layer name and geometry type, and press OK

<figure><img src="https://lh5.googleusercontent.com/H1cGGtrsYwaHw9RCYIU-AJ-vGm7c8Ct5tC5HVnVx96Ev-nYa3gleJ6joKrX-6zfIKMF50eBmI2MPFJ4FEmam9gvjKFq-ovVxhw7FhecUnH6Xf1OQ2MA87t-8H_km6cpYEySZqQW_DZV79YLClPDPeg" alt=""><figcaption></figcaption></figure>

#### 4 - Select the layer in the Layers panel

1. Select “Toggle Editing” (1)
2. Select “Add Polygon Feature” (2)

#### 5 - Draw a polygon. To finish drawing press the right mouse button and set “id” in the popup.

Finish the layer by pressing “Toggle Editing” again and press “Save”.

<figure><img src="https://lh3.googleusercontent.com/3qiSZYB3e8c_froqsv59x8tU9mMKIh3cvC6Tlv9xyZDZQc6d5AGZXylBVGBvnypyDVXJvbUsqNVe5p8aF8mS0VnSCPPTwqsIvAVYmnZYAlGgBnVu5od_5C1oU3IwDwpUpcJhWpbDrMzI46UgaeLtTg" alt=""><figcaption></figcaption></figure>

#### 6 - Select Zonal statistics in the “Processing toolbox” panel.

<figure><img src="https://lh3.googleusercontent.com/qdPIGWoz8W2id9mXwjo-7AnbX8RWSpMnEdhFtIzR4fq07Po3Jg2Wmn0-4Ucgihk_04H2VJsQraYPSE8f6MHB0cjtMD2VAsMe8ILf6vu-gtCXFor7pGVg-1-vus8OXx2MyY2Ogb4LVMxcpB7Hkp5sHw" alt=""><figcaption></figcaption></figure>

#### 7 - Select raster layer (1),

Select polygon layer (2),

Press “Run” (3).

<figure><img src="https://lh3.googleusercontent.com/htEYAd45WO6Rcw8rHMQ4W7rO4CdjsyxiHP_7Wb2gUan1Dw_szsi43ePRS6x8lHhAA8JeklNUfPEm3Xh6nXnoDJaiXq3eMGwqSOC2Yb-qvnUhOIInsMhCe_ImYHEv7MS60ZkXYoaXkJiKBIOTUskbTQ" alt=""><figcaption></figcaption></figure>

#### 8 - Select the layer in the Layers panel and press the right mouse button, in the context menu select Open Attribute Table.

<figure><img src="https://lh3.googleusercontent.com/Oc1SLXwTAYBzZUrFq3TOAnF2p9UROQ28Cv6wv3XXhLkS5LGYRNoZ-JD_HIjDt-9FEiAzQLXjehiIyjZielJtB6-F0ohTMz3gTbsoZ02vanuuv37voF72i1h3p8YQBuhgfpt6hCcTguhM3-AujNSV_A" alt=""><figcaption></figcaption></figure>

#### 9 - Calculated statistics will be shown in the table.<br>