{"id":468,"date":"2014-06-29T22:44:36","date_gmt":"2014-06-29T22:44:36","guid":{"rendered":"http:\/\/www.iskort.is\/?p=468"},"modified":"2014-06-29T22:44:36","modified_gmt":"2014-06-29T22:44:36","slug":"vinnsla-a-grodurthekju","status":"publish","type":"post","link":"https:\/\/www.iskort.is\/?p=468","title":{"rendered":"Vinnsla \u00e1 gr\u00f3\u00f0ur\u00feekju"},"content":{"rendered":"

N\u00fana stendur yfir heilmikil yfirfer\u00f0 \u00e1 Landsat 8 gerfihnattamyndum \u00ed \u00feeim tilgangi a\u00f0 n\u00e1 \u00fat heildst\u00e6\u00f0ri gr\u00f3\u00f0ur\u00feekju af landinu.<\/p>\n

Landsat 8 gagnasafn samanstendur af 11 mismunandi myndum af hverju sv\u00e6\u00f0i, teknum \u00e1 sama t\u00edma. – Munurinn \u00e1 myndunum felst \u00ed mismunandi t\u00ed\u00f0nisvi\u00f0i sem vi\u00f0komandi mynd er tekin \u00e1.<\/p>\n

H\u00e9r er sk\u00fdringarmynd sem s\u00fdnir t\u00ed\u00f0nisvi\u00f0 hvers „litabands“ \u00ed gagnasafninu. Einungis l\u00edtill hluti af af t\u00ed\u00f0nisvi\u00f0inu er s\u00fdnilegt lj\u00f3s (bl\u00e1r, gr\u00e6nn, rau\u00f0ur). \u00d6nnur b\u00f6nd eins og t.d infrarau\u00f0ur er nota\u00f0ur til a\u00f0 vinna gr\u00f3\u00f0ur\u00feekju og band 1 t.d nota\u00f0 til a\u00f0 vinna vatnsyfirbor\u00f0.<\/p>\n

\"landsat8\"<\/a><\/p>\n

Efri r\u00f6\u00f0in s\u00fdnir Landsat 8 b\u00f6nd, en s\u00fa ne\u00f0ri eldri Landsat 7 b\u00f6nd.<\/p>\n

Gr\u00f3\u00f0ur\u00feekjan (NDVI)\u00a0 er fengin \u00fat bandi 4(Red) og bandi 5 (NIR, Near Infrared) me\u00f0 \u00e1kve\u00f0inni form\u00falu :<\/p>\n

NDVI = ((NIR - Red)\/(NIR + Red))<\/pre>\n
Reikna \u00fearf \u00fat gr\u00f3\u00f0ur\u00feekjuna fyrir hverja mynd fyrir sig og einnig \u00fearf a\u00f0 taka \u00fat sv\u00e6\u00f0i sem eru \u00feakin sk\u00fdjum.<\/p>\n
Landsat 8 gagnasafni\u00f0 inniheldur s\u00e9rstakt band sem endurspeglar g\u00e6\u00f0i hvers pixels \u00ed vi\u00f0komandi mynd og er h\u00e6gt a\u00f0 lesa \u00fat \u00fdmisskonar uppl\u00fdsingar \u00far g\u00e6\u00f0abandinu. St\u00f6k gildi \u00ed skr\u00e1nni eru t.d fyrir l\u00e1gsk\u00fd, h\u00e1sk\u00fd, \u00eds, snj\u00f3, og vatn og land.<\/p>\n
 <\/p>\n
H\u00e9r fyrir ne\u00f0an eru s\u00fdnishorn \u00ed l\u00e1gri upplausn af hverri \u00feekju og \u00feeim \u00ferepum \u00ed vinnslunni sem eru til a\u00f0 f\u00e1 \u00fat sk\u00fdjalausa gr\u00f3\u00f0ur\u00feekju.<\/p>\n
\u00dear sem sk\u00fdja\u00f0 er, \u00fearf a\u00f0 finna a\u00f0ra mynd tekna \u00e1 \u00f6\u00f0rum t\u00edma, \u00fear sem sv\u00e6\u00f0i\u00f0 er sk\u00fdjalaust. Leggja\u00a0 \u00fearf svo myndirnar saman til a\u00f0 f\u00e1 heilst\u00e6\u00f0a sk\u00fdjalausa \u00feekju af \u00f6llu landinu.<\/p>\n
Hver mynd \u00feekur um 37 ferk\u00edl\u00f3metra og \u00fev\u00ed eru heilmargar myndir sem \u00fearf til a\u00f0 \u00feekja allt landi\u00f0 og enn\u00fe\u00e1 fleiri til a\u00f0 n\u00e1 \u00f6llum sv\u00e6\u00f0um sk\u00fdjalausum.<\/p>\n
\"Band-4\"<\/a>
\n\u00deekja sem endurspeigar rau\u00f0an lit<\/p>\n
\"Band-5\"<\/a>
\n\u00deekja sem endurspeglar infrarau\u00f0an lit<\/p>\n
\"NDVI\"
\n<\/a>NDVI \u00feekja sem endurspeglar hvar gr\u00f3\u00f0ur er (gr\u00e6nn), og \u00eds\/vatn (Bl\u00e1r)<\/p>\n
\"Band-BQA\"<\/a>
\nG\u00e6\u00f0a\u00feekjan. Mismunandi litir endurspegla mismunandi g\u00e6\u00f0i \u00e1 hverjum pixel og yfirbor\u00f0stegund<\/p>\n
\"Band-BQA-Filtered\"<\/a>
\n\u00deekja \u00fear sem sk\u00fdlaus sv\u00e6\u00f0i hafa veri\u00f0 merkt gr\u00e6n.<\/p>\n
\"NDVI-Clouds\"<\/a>
\nG\u00e6\u00f0a\u00feekjan l\u00f6g\u00f0 yfir gr\u00f3\u00f0ur\u00feekjuna \u00fear sem eing\u00f6ngu sk\u00fdjalaust sv\u00e6\u00f0i skilar s\u00e9r \u00ed gegn.<\/p>\n
\"Greens-Clouds\"<\/a>
\nGr\u00f3\u00f0ur (gr\u00e6nn) a\u00f0skilin fr\u00e1 NDVI myndinni (Bl\u00e1r tekinn fr\u00e1) og \u00fat kemur \u00feekja sem endurspeglar magn gr\u00f3\u00f0urs.<\/p>\n
 <\/p>\n","protected":false},"excerpt":{"rendered":"
N\u00fana stendur yfir heilmikil yfirfer\u00f0 \u00e1 Landsat 8 gerfihnattamyndum \u00ed \u00feeim tilgangi a\u00f0 n\u00e1 \u00fat heildst\u00e6\u00f0ri gr\u00f3\u00f0ur\u00feekju af landinu. Landsat 8 gagnasafn samanstendur af 11 mismunandi myndum af hverju sv\u00e6\u00f0i, teknum \u00e1 sama t\u00edma. – Munurinn \u00e1 myndunum felst \u00ed mismunandi t\u00ed\u00f0nisvi\u00f0i sem vi\u00f0komandi mynd er tekin \u00e1. H\u00e9r er sk\u00fdringarmynd sem s\u00fdnir t\u00ed\u00f0nisvi\u00f0 hvers … Lesa \u00e1fram Vinnsla \u00e1 gr\u00f3\u00f0ur\u00feekju<\/span> →<\/span><\/a><\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[1],"tags":[],"class_list":["post-468","post","type-post","status-publish","format-standard","hentry","category-oflokkad"],"_links":{"self":[{"href":"https:\/\/www.iskort.is\/index.php?rest_route=\/wp\/v2\/posts\/468","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.iskort.is\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.iskort.is\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.iskort.is\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.iskort.is\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=468"}],"version-history":[{"count":3,"href":"https:\/\/www.iskort.is\/index.php?rest_route=\/wp\/v2\/posts\/468\/revisions"}],"predecessor-version":[{"id":481,"href":"https:\/\/www.iskort.is\/index.php?rest_route=\/wp\/v2\/posts\/468\/revisions\/481"}],"wp:attachment":[{"href":"https:\/\/www.iskort.is\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=468"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.iskort.is\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=468"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.iskort.is\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=468"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}