[RS-ecology] RS-ecology Digest, Vol 16, Issue 1

Benjamin Leutner benjamin.leutner at uni-wuerzburg.de
Mon Dec 12 16:11:55 CET 2016


Hi Dragan,

for your first question: yes,  spectralIndices can be calculated on 
Sentinel 2 images as well and L1C data are indeed top of atmosphere 
reflectance.
Just for calculating spectral indices in principle there's no need for 
further conversions. Nevertheless, it is a good idea to perform 
atmospheric correction on Sentinel 2 data beforehand (with ESA SNAP 
software and/or SEN2COR), because this should improve comparability 
among different scenes.

for your last question. the data() function is out of place here.
Your code should read:
bs3 <- raster("C:/R_examples/VI/B3.TIF")
bs4 <- raster("C:/R_examples/VI/B4.TIF")
group <- stack(bs3, bs4)
names(group) <- c("bs3", "bs4")# make proper names
ndvi <- spectralIndices(group, red = "bs3", nir = "bs4", indices = "NDVI")


Cheers,
Benjamin


On 12/12/2016 03:45 PM, Dragan Kaludjerovic wrote:
> Martin,
> I have replaced brick() with stack() and still got the error when I 
> run the line data. Here is how it looks now:
>
> install.packages("RStoolbox")
> install.packages(raster)
>
> library(ggplot2)
> library(raster)
> library(rgdal)
>
> bs3 <- raster("C:/R_examples/VI/B3.TIF")
> bs4 <- raster("C:/R_examples/VI/B4.TIF")
>
> bs3
> bs4
>
> group <- stack(bs3, bs4)
>
> #writeRaster(group, filename = "C:/R_examples/VI/grupa.TIF")
>
> data(group)
>
> ## Calculate NDVI
>
> ndvi <- spectralIndices(group, red = "bs3", nir = "bs4", indices = "NDVI")
>
> ndvi
>
> eror when I run line data(group)
>
> Warning message: In data(group) :data set ‘group’ not found
>
> On Mon, Dec 12, 2016 at 8:17 AM, Martin Wegmann 
> <martin.wegmann at uni-wuerzburg.de 
> <mailto:martin.wegmann at uni-wuerzburg.de>> wrote:
>
>     Dear Dragan,
>
>     Please replace brick() with stack() and it should work, and of
>     course you need to adapt your band names in spectralIndices()‎.
>
>     Regards, Martin
>
>     *From: *Dragan Kaludjerovic
>     *Sent: *Sunday, December 11, 2016 23:21
>     *To: *rs-ecology at lists.uni-wuerzburg.de
>     <mailto:rs-ecology at lists.uni-wuerzburg.de>
>     *Subject: *Re: [RS-ecology] RS-ecology Digest, Vol 16, Issue 1
>
>
>     Now I have changed it, but still getting error
>
>     install.packages("RStoolbox")
>     install.packages(raster)
>
>     library(ggplot2)
>     library(raster)
>     library(rgdal)
>
>     bs3 <- raster("C:/R_examples/VI/B3.TIF")
>     bs4 <- raster("C:/R_examples/VI/B4.TIF")
>
>     bs3
>     bs4
>
>     group <- brick(bs3, bs4)
>
>     data(group)
>
>     ## Calculate NDVI
>
>     ndvi <- spectralIndices(group, red = "bs3", nir = "bs4", indices =
>     "NDVI")
>
>     ndvi
>
>     error is:
>
>
>     >group <- brick(bs3, bs4) > data(group) Warning message: In
>     data(group) :data set ‘group’ not found
>
>
>     On Sun, Dec 11, 2016 at 12:00 PM,
>     <rs-ecology-request at lists.uni-wuerzburg.de
>     <mailto:rs-ecology-request at lists.uni-wuerzburg.de>> wrote:
>
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>         Today's Topics:
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>            1. problem with RStoolbox (Dragan Kaludjerovic)
>            2. Re: problem with RStoolbox (Martin Wegmann)
>
>
>         ----------------------------------------------------------------------
>
>         Message: 1
>         Date: Sat, 10 Dec 2016 19:00:11 +0100
>         From: Dragan Kaludjerovic <advancedgwt at gmail.com
>         <mailto:advancedgwt at gmail.com>>
>         To: RS-ecology at lists.uni-wuerzburg.de
>         <mailto:RS-ecology at lists.uni-wuerzburg.de>
>         Subject: [RS-ecology] problem with RStoolbox
>         Message-ID:
>                
>         <CAFZvhLipaCHuq-hQsk_5i31ThbCXGQZ4cPhP87+YS4P6__rzDw at mail.gmail.com
>         <mailto:CAFZvhLipaCHuq-hQsk_5i31ThbCXGQZ4cPhP87%2BYS4P6__rzDw at mail.gmail.com>>
>         Content-Type: text/plain; charset="utf-8"
>
>         Hi,
>         I have just discover RStoolbox and try simple simple script
>
>         install.packages("RStoolbox")
>         install.packages(raster)
>
>         library(ggplot2)
>         library(raster)
>         library(rgdal)
>
>         data(img)
>
>         ## Calculate NDVI
>         ndvi <- spectralIndices(img, red = "C:/R_examples/VI/B3.tif",
>         nir =
>         "C:/R_examples/VI/B4.tif", indices = "NDVI")
>         ndvi
>
>
>         when I run it I got error message
>
>         Error in match(xi, names(img)) : object 'img' not found
>
>         Any suggestion is welcomed!
>
>         Best Regards,
>
>         Dragan
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>         Message: 2
>         Date: Sun, 11 Dec 2016 09:46:02 +0100
>         From: Martin Wegmann <martin.wegmann at uni-wuerzburg.de
>         <mailto:martin.wegmann at uni-wuerzburg.de>>
>         To: Dragan Kaludjerovic <advancedgwt at gmail.com
>         <mailto:advancedgwt at gmail.com>>,
>         RS-ecology at lists.uni-wuerzburg.de
>         <mailto:RS-ecology at lists.uni-wuerzburg.de>
>         Subject: Re: [RS-ecology] problem with RStoolbox
>         Message-ID:
>         <20161211084602.5943378.73264.3393 at uni-wuerzburg.de
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>         End of RS-ecology Digest, Vol 16, Issue 1
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-- 
Benjamin Leutner M.Sc.
PhD candidate

Department of Remote Sensing
University of Wuerzburg
Campus Hubland Nord 86
97074 Wuerzburg, Germany

Tel: +49-(0)931-31 89594
Fax: +49-(0)931-31 89594-0
Email: benjamin.leutner at uni-wuerzburg.de
Web: http://www.fernerkundung.uni-wuerzburg.de

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