Dear sir,
Actually I realize that 0.02 tolerance is the best that incorporate the
variation in X coordinates differences. Then I used the points2grid with
tolerance=0.02 it worked till this step but as soon as I use the code:
gridded(A)<-TRUE
then same error message appeared. so that means the problem should solved for
gridded too but i don't know how to do it.
its strange to found that why there is inconsistency in the X value
differences! for the other data that have been extracted Using ENVI to text
format are consistent and dont give any problem. This data set being spatially
bit finner (4.7mx 4.7m) may be the reason for the cuasue of inconsistency while
exporting from ENVI.
Thanking you
Pujan
> Date: Fri, 2 May 2008 20:34:06 +0200> From: [EMAIL PROTECTED]> To: [EMAIL
> PROTECTED]> CC: r-sig-geo@stat.math.ethz.ch> Subject: RE: [R-sig-Geo] Scale
> Bar> > On Fri, 2 May 2008, PUJAN RAJ REGMI wrote:> > >> >> > Dear sir,> > My
> data has been acquired from ENVI 4.0 and it has the following information
> regarding pixel size and projection system:> > samples = 596lines = 440bands
> = 21> > pixel size: 4.710294*4.70871> > file type = ENVI Standard> > header
> offset = 0> > map info = {UTM, 1.000, 1.000, 564761.521, 5699816.363,
> 4.7102936126e+000, 4.7087100663e+000, 31, North, WGS-84, units=Meters}> >> >
> vitotagprojectionsystem = Universal_Transverse_Mercatorvitotagprojectiondatum
> = WGS_84vitotagprojectionzone = 31> > I was mistaken earlier that projection
> datum was Eueropean1950 instead it is WGS84> > so I think the projection code
> should be:> > proj4string(A) <- CRS("+proj=utm +zone=31 +ellps=WGS84")> > Or
> perhaps> > proj4string(A) <- CRS("+proj=utm +zone=31 +datum=WGS84")>!
> to fix the datum and ellipse at one go.> > > Regarding the tolerance
problem; The difference in the X coordinates > > (column 1 out of 21
column)varies from 4.7019876 to 4.719234 so the > > default tolerance
0.00212314227724164 does not incorporate those > > variation. This is my source
of error. Thanking you in advance Pujan> > The given value is an internal
value, but indicates what may be set to > correct the problem. Do you know why
the differences in the x coordinates > vary? These look too big to be rounding
error. I believe that the current > points2grid will not solve the problem, but
am working on a solution.> > Another question is whether you could transfer
data from ENVI to R using a > different file format, for example as a GTiff,
and the read it using > readGDAL() in rgdal?> > Roger> > >> >> Date: Fri, 2 May
2008 19:49:07 +0200> From: [EMAIL PROTECTED]> To: [EMAIL PROTECTED]> CC:
r-sig-geo@stat.math.ethz.ch> Subject: RE: [R-sig-Geo] Scale Bar> > On F!
ri, 2 May 2008, PUJAN RAJ REGMI wrote:> > >> >> > Dear list,> > Thanks
to Mr. Roger, I have now able to plot my data using image and sp > > packages.
Everything now seems ok for one type of data set where X and Y > > coordinates
are regularly spaced with tolerance less than 0.000002. Now > > I tried to plot
with another data set then soon I realize that X > > coordinates have tolerance
about 0.02. This thing I realize when I get > > the error message as follows:
?gridded(A)<- TRUE suggested tolerance > > minimum: 0.00212314227724164Error in
points2grid(points, tolerance) : > > dimension 1 : coordinate intervals are not
constant? Then I tried to use > > points2grid to overcome this problem but it
did not work.> > Do you know where the irregular values came from - type of
file written by > what software? Are they just rounding at some stage - I feel
that it would > be helpful to rule out real causes before correcting something
that might > be an actual mistake, if you see what I mean.> > >> > One more
question my data has a projection system UTM!
(European1950) ZONE31.> > How can I incorporate this information while
converting spatial data?> > proj4string(A) <- CRS("+proj=utm +zone=31
+ellps=intl")> > but because ED50 is not well defined, there is no +towgs84=
value in the > EPSG database in the rgdal package. If you need to
datum-transform spatial > data (not the grid, obviously), you'll need the
+towgs84 values for your > location.> > Roger> > > Thanking you> > Pujan> >> >>
Date: Fri, 2 May 2008 11:29:37 +0200> From: [EMAIL PROTECTED]> To: [EMAIL
PROTECTED]> CC: r-sig-geo@stat.math.ethz.ch> Subject: Re: [R-sig-Geo] Scale
Bar> > On Thu, 1 May 2008, PUJAN RAJ REGMI wrote:> > > Dear,> > > I followed
the instruction given by Roger. But i got the following error > > message;
coordinates(A) <- c("x", "y")> gridded(A) <- TRUE> > >
greenchannel<-matrix(A[,3],nrow=155,ncol=191,byrow=TRUE)Error in > >
as.vector(x, mode) : cannot coerce to > >
vectorredchannel<-matrix(A[,4],nrow=155,ncol=191,byrow=TRUE)Error in > > !
as.vector(x, mode) : cannot coerce to vector> > > nearinfraredchannel<
-matrix(A[,5],nrow=155,ncol=191,byrow=TRUE)Error in > > `[.data.frame`([EMAIL
PROTECTED], i, j, ..., drop = FALSE) : undefined columns > > selected> > >
midinfraredchannel<-matrix(A[,6],nrow=155,ncol=191,byrow=TRUE)Error in > >
`[.data.frame`([EMAIL PROTECTED], i, j, ..., drop = FALSE) : undefined columns
> > selectedThe image plot was black background with x and y axis values.> >
You are not reading what is being sent to you carefully enough, but at > least
this is a fresh thread, so some progress. Above, you have mixed up > my answer
with your own attempt to use rimage classes and functions. If > you have
spatial data, use spatial classes and functions, which permit > integration
with other spatial data.> > Using the data you sent me offline (but *.rar
compressed, please use gzip > or zip, rar is not portable), I have:> > > A <-
read.table("test.txt", skip=8, header=FALSE)> names(A) <- c("x", "y",
"greenchannel", "redchannel",> "nearinfraredchannel", "midinfraredchannel")>
coordinates(A) <- c("!
x", "y")> gridded(A) <- TRUE> > I note that you have not given the projection
of your data (UTM?), so > registering this data with other data (stream channel
patterns?) is not > made any easier.> > A$red <-
as.double(A$nearinfraredchannel)> A$green <- as.double(A$redchannel)> A$blue <-
as.double(A$greenchannel)> summary(A)> > The values appear to be in the 0-255
range, but do not go much beyond > halfway - do they need stretching?
Muliplying the values by 1.79 -> 1/(max(c(A$red, A$green, A$blue))/255) rounded
down a touch - gave a more > pleasing image, but I don't know the origins of
your data.> > image(A, red="red", green="green", blue="blue", axes=TRUE)> >
which shows the majority of your study area as 0 coded black, and the >
remainder is not very differentiated. It ought to be possible to code > these 0
values as NA, but currently the underlying method in sp does not > handle NAs
gracefully for rgb input - this will be improved in the next > release. So, we
recode 0 as!
255 to get white:> > A$red <- ifelse(A$red < 1, 255, A$red)> A$green
<- ifelse(A$green < 1, 255, A$green)> A$blue <- ifelse(A$blue < 1, 255,
A$blue)> image(A, red="red", green="green", blue="blue", axes=TRUE)> > So now
to your scale bar:> > SpatialPolygonsRescale(layout.scale.bar(), offset =
c(566500, 5698000),> scale = 500, fill=c("transparent","black"),
plot.grid=FALSE)> text(566500, 5698075, "0", cex=0.7)> text(567000, 5698075,
"500 m", cex=0.7)> > You can complete the north arrow in the same way using
examples on the > help page for spplot, if you really want one.> > Finally, as
a geographer, I would point out that the scale bar and north > arrow are not
needed when the axes show the scale and the direction of > north. Anyone who
tells you that they have to be there (your supervisor?), > should read up on
analytical graphics - extra details distract attention > from what the data are
saying. Probably using grid() is less intrusive, > and gives good placing
control across the whole graphic. When was the last > time anyone actually used
a m!
ap scale bar to read off distances from a > map?> > Roger> > > > Any help?> >
Thanking you> > Pujan> >
_________________________________________________________________> > Back to
work after baby?how do you know when you?re ready?> >> >
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-- > Roger Bivand> Economic Geography Section, Department of Economics,
Norwegian School of> Economics and Business Administration, Helleveien 30,
N-5045 Bergen,> Norway. voice: +47 55 95 93 55; fax +47 55 95 95 43> e-mail:
[EMAIL PROTECTED]> >
_________________________________________________________________> > Get Free
(PRODUCT) RED? Emoticons, Winks and Display Pics> >
http://joinred.spaces.live.com?ocid=TXT_HMTG_prodredemoticons_052008> > -- >
Roger Bivand> Economic Geography Section, Department of Economics, Norwegian
School of> Economics and Business Administration, Helleveien 30, N-5045
Bergen,> Norway. voice: +47 55 95 93 55; fax +47 55 95 95 43> e-mail: !
[EMAIL PROTECTED]> > _______________________________________________
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> -- > Roger Bivand> Economic Geography Section, Department of Economics,
Norwegian School of> Economics and Business Administration, Helleveien 30,
N-5045 Bergen,> Norway. voice: +47 55 95 93 55; fax +47 55 95 95 43> e-mail:
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