# QGIS: calcola l'NDVI per il file GeoTIFF del drone

A volte è necessario calcolare la NDVI media per un poligono all’interno del campo. È possibile fare quanto segue in un programma QGIS.<br>

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

#### 1 - Visualizza il geotiff NDVI iniziale del drone

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

#### 2 - Crea un nuovo layer

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

#### 3 - Imposta il nome del layer e il tipo di geometria, quindi premi OK

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

#### 4 - Seleziona il layer nel pannello Layer

1. Seleziona “Attiva modifica” (1)
2. Seleziona “Aggiungi feature poligonale” (2)

#### 5 - Disegna un poligono. Per terminare il disegno premi il tasto destro del mouse e imposta “id” nel popup.

Termina il layer premendo di nuovo “Attiva modifica” e premi “Salva”.

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

#### 6 - Seleziona Statistiche zonali nel pannello “Casella degli strumenti di elaborazione”.

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

#### 7 - Seleziona il layer raster (1),

Seleziona il layer poligonale (2),

Premi “Esegui” (3).

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

#### 8 - Seleziona il layer nel pannello Layer e premi il tasto destro del mouse; nel menu contestuale seleziona Apri tabella degli attributi.

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

#### 9 - Le statistiche calcolate verranno mostrate nella tabella.<br>


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