{"id":8292,"date":"2019-03-15T01:59:42","date_gmt":"2019-03-15T00:59:42","guid":{"rendered":"http:\/\/www.sigterritoires.fr\/?p=8292"},"modified":"2019-03-15T07:12:05","modified_gmt":"2019-03-15T06:12:05","slug":"how-to-use-landsat-images-free-with-arcgis-arcmap-for-ndvi","status":"publish","type":"post","link":"https:\/\/www.sigterritoires.fr\/index.php\/en\/how-to-use-landsat-images-free-with-arcgis-arcmap-for-ndvi\/","title":{"rendered":"How to use Landsat Images ( Free ) with ArcGis (ArcMap) for NDVI"},"content":{"rendered":"\n

In a previous\narticle,   How to use Landsat images (\nfree ) in<\/a> your GIS<\/a> , we discuss how\nto download Landsat 7 or 8 images. Now we will discuss\nhow to use them with ArcGis, when you use ArcMap or ArcGis Pro.\n<\/p>\n\n\n\n

We left at the point where you had , in a\ndirectory\n, a series of 8   or 11\ntiff images. Each of\nthem corresponds to a satellite band .\nLandsat 7 images have 8   bands\nwhile the Landsat 8 have 11. <\/p>\n\n\n\n

For the calculation of the NDVI<\/a>\nyou\nwill\nneed\nthe band corresponding to the red and the\nnear infra-red: <\/p>\n\n\n\n\n\n\n\n

For Landsat 7 the red band is N \u00b0 3 and the\ninfra- red is N \u00b0 4 <\/p>\n\n\n\n

For Landsat 8   the\nred is N \u00b0 4 and the infra- red is N \u00b0 5\n<\/p>\n\n\n\n

We could calculate directly\nthe NDVI by entering its formula in the raster calculator , by\nusing the two corresponding tiff images . But you\nArcGis allows you to, directly, calculate NDVI on an image,\nprovided it contains the necessary bands and, in general\n, we, also, wish to\u00a0\u00bb see \u00a0\u00bb the optical\nimage (RGB) and not only the NDVI calculation. <\/p>\n\n\n\n

How to create<\/strong>\na<\/strong> composite image<\/strong> from<\/strong> the<\/strong> different<\/strong>\nbands<\/strong>\n<\/p>\n\n\n\n

Therefore we will start by creating\na\ncomposite image containing the three bands of the visible spectrum (RGB) and\nthe band corresponding to the infra -red. \n\nEach of these four bands\nare\nin a separate image, we will use a\ntoolbox\ntool to create a single composite image. \n\n\n\n<\/p>\n\n\n\n

\"\"<\/figure>\n\n\n\n

You will find the command \u00ab\u00a0Composite channels\u00a0\u00bb\nin the toolbox \u00ab\u00a0Data Management\u00a0\u00bb -> Raster -> Raster Processing\n\n\nIf you use ArcGis Pro, the same\ntool\nis\navailable\nin\nthe Geoprocessing window .  \n\n\n\n<\/p>\n\n\n\n

\"\"<\/figure>\n\n\n\n

Select the four bands\nwhose\nnames end with B1, B2, B3 and B4.
\nUsing\nthe arrows change the\norder of the images to match the order of the optical images (RGB- Ir), ie B3\nfirst, then B2, and B1 finally B4. <\/p>\n\n\n\n

If you do not save the image in\na\ngeodatabase, do not forget to add the .tif extension to the\noutput name. \n\nThe result of the command is loaded in the ArcMap\nwindow . \n\n\n\n<\/p>\n\n\n\n

\"\"<\/figure>\n\n\n\n

How to calculate<\/strong> and display the<\/strong> NDVI<\/strong> <\/p>\n\n\n\n

To calculate the NDVI index , just open the ArcMap Image Analysis window: <\/p>\n\n\n\n

\"\"<\/figure>\n\n\n\n

Before proceeding with the calculation , the bands to be used have to be\nconfigured. <\/p>\n\n\n\n

  • Click the \u00ab\u00a0Options\u00a0\u00bb icon at the left top. <\/li>
  • In the NDVI index tab enter 1 as the red channel and 4 as the\ninfra-red channel. <\/li>
  • Check the Scientific Output tab to get the results between -1 and 1. If not, you will have the NDVI between 0 and 255. <\/li><\/ul>\n\n\n\n

    \n\n\n\n\n\nClose the window options .
    \nThe display of the NDVI index is performed by clicking on the fourth treatment\nblock icon (the green Maple leaf ). \n\n\n\n<\/p>\n\n\n\n

    \"\"<\/figure>\n\n\n\n

    How to create<\/strong> a<\/strong> customized<\/strong> symbology for<\/strong> the<\/strong> NDVI<\/strong> display<\/strong> <\/p>\n\n\n\n

    The default symbology is in shades of gray . To apply a more \u00ab\u00a0standard\u00a0\u00bb symbology you have to create a color gradient in ArcMap. This \u00ab\u00a0standard\u00a0\u00bb symbology depicts the negative values of NDVI in shades of blue and the positive values in a red to green gradient with yellow. <\/p>\n\n\n\n

    \"\"<\/figure>\n\n\n\n

    This operation only has to be performed the first time .  \n\nTo create the customized gradient:\n\n\n\n<\/p>\n\n\n\n

    \"\"<\/figure>\n\n\n\n

    In the ArcMap menu, click Customize -> Styles Manager
    \nOpen the personal styles folder (take care not to open the ESRI folder )
    \nSelect \u00ab\u00a0color gradients\u00a0\u00bb
    \nRight-click the right window
    \nSelect \u00ab\u00a0New\u00a0\u00bb from the menu -> Blend multipart colors <\/p>\n\n\n\n

    We are going to create two sections for the gradient : the first for the blue\ngradients, the second for the green to red gradient. \n\nClick on \u201cAdd\u201d     \n\n\n\n<\/p>\n\n\n\n

    \"\"<\/figure>\n\n\n\n

    Then select \u00a0\u00bb Algorithmic Colors Gradient \u00a0\u00bb
    By default, a shading is added to the window . Click on \u00a0\u00bb Properties \u00ab\u00a0. In \u00a0\u00bb Color 1 select a dark blue . In color 2 select a light blue in the same column only as the dark blue.<\/strong><\/p>\n\n\n\n

    \"\"<\/figure>\n\n\n\n

    Click again on \u00a0\u00bb Add \u00a0\u00bb
    Then select \u00a0\u00bb Algorithmic colors gradient \u00a0\u00bb
    Click on \u00a0\u00bb Properties \u00ab\u00a0. In \u00a0\u00bb Color 1 select a bright green . In color 2 select the red in the same line as green.<\/strong> The yellow should be on this line . \u00a0\u00a0 <\/p>\n\n\n\n

    \"\"<\/figure>\n\n\n\n

    Click OK and OK
    \nRename\nthe \u00ab\u00a0NDVI\u00a0\u00bb gradient<\/p>\n\n\n\n

    We are done! The gradient will\nappear in the gradient dropdown window of the ArcMap layer\nsymbology . <\/p>\n","protected":false},"excerpt":{"rendered":"

    In a previous article,   How to use Landsat images ( free ) in your GIS , we discuss how to download Landsat 7 or 8 images. Now we will discuss how to use them with…<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"give_campaign_id":0,"_bbp_topic_count":0,"_bbp_reply_count":0,"_bbp_total_topic_count":0,"_bbp_total_reply_count":0,"_bbp_voice_count":0,"_bbp_anonymous_reply_count":0,"_bbp_topic_count_hidden":0,"_bbp_reply_count_hidden":0,"_bbp_forum_subforum_count":0,"sfsi_plus_gutenberg_text_before_share":"","sfsi_plus_gutenberg_show_text_before_share":"","sfsi_plus_gutenberg_icon_type":"","sfsi_plus_gutenberg_icon_alignemt":"","sfsi_plus_gutenburg_max_per_row":"","_monsterinsights_skip_tracking":false,"_monsterinsights_sitenote_active":false,"_monsterinsights_sitenote_note":"","_monsterinsights_sitenote_category":0,"_jetpack_newsletter_access":"","_jetpack_dont_email_post_to_subs":false,"_jetpack_newsletter_tier_id":0,"_jetpack_memberships_contains_paywalled_content":false,"_jetpack_memberships_contains_paid_content":false,"footnotes":"","jetpack_post_was_ever_published":false},"categories":[1260],"tags":[],"class_list":["post-8292","post","type-post","status-publish","format-standard","hentry","category-non-classe-en"],"aioseo_notices":[],"jetpack_featured_media_url":"","jetpack_shortlink":"https:\/\/wp.me\/p6XU0A-29K","jetpack_sharing_enabled":true,"_links":{"self":[{"href":"https:\/\/www.sigterritoires.fr\/index.php\/wp-json\/wp\/v2\/posts\/8292","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.sigterritoires.fr\/index.php\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.sigterritoires.fr\/index.php\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.sigterritoires.fr\/index.php\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.sigterritoires.fr\/index.php\/wp-json\/wp\/v2\/comments?post=8292"}],"version-history":[{"count":0,"href":"https:\/\/www.sigterritoires.fr\/index.php\/wp-json\/wp\/v2\/posts\/8292\/revisions"}],"wp:attachment":[{"href":"https:\/\/www.sigterritoires.fr\/index.php\/wp-json\/wp\/v2\/media?parent=8292"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.sigterritoires.fr\/index.php\/wp-json\/wp\/v2\/categories?post=8292"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.sigterritoires.fr\/index.php\/wp-json\/wp\/v2\/tags?post=8292"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}