shapefiles, images, iimagemaps, and removinginternalboundarylines

Thanks Roger,

I'll try and build my own from source -- I was just hoping there was a
binary floating around somewhere.

Truthfully, my maps will have very detailed boundaries (Relatively
speaking, I think), so I'll give it a try.
A possible dirty fix is to overlay the polygons with a low-resolution grid 
and take the convex hull of cell centres within each polygon as the object 
passed to the HTML code as a clickable mask - there will be "no-hit" 
slivers, and overlaps for convex/concave boundaries, but life is too short 
...

library(maptools)
xx <- readShapePoly(system.file("shapes/sids.shp", package="maptools")[1], 
  IDvar="FIPSNO", proj4string=CRS("+proj=longlat +ellps=clrk66"))
grd <- GridTopology(c(-84.5, 33.75), c(0.025, 0.025), c(360, 120))
mask <- SpatialGrid(grd, proj4string=CRS("+proj=longlat +ellps=clrk66"))
where <- overlay(mask, xx) # takes some time
incrds <- coordinates(mask)[!is.na(where),]
inwhere <- where[!is.na(where)]
incrds1 <- split(data.frame(incrds), inwhere)
chulls <- lapply(incrds1, function(x) {xx <- as.matrix(x); 
  xx[chull(xx),]})
plot(xx, border="blue")
lapply(chulls, polygon, col="yellow")

There are slivers/overlaps, it'll need fine tuning, but these image map 
polygons have many fewer boundary points that the originals. In addition 
multiple polygon objects are not treated gracefully. 

Roger
I'll be posting some more questions in a bit about
'unionSpatialPolygons', as I am having some troubles with it...

Thanks,
Matt 

-----Original Message-----
From: Roger Bivand [mailto:Roger.Bivand at nhh.no] 
Sent: Thursday, October 19, 2006 2:57 PM
To: Pettis, Matthew (TLR Corp)
Cc: r-sig-geo at stat.math.ethz.ch
Subject: RE: [R-sig-Geo] shapefiles, images, iimagemaps, and
removinginternalboundarylines

On Thu, 19 Oct 2006 matt.pettis at thomson.com wrote:

Thanks! Got it to work.

However, the install of "imagemap" didn't work for me... I'm on 
Windows XP, and the souce comes in a .tar.gz file, which the 'Packages

Install
packages(s) from local .zip files...' doesn't recognize.  Any 
alternate location for this, or a method for windows xp to import this

module correctly?
The *.tar.gz is a source package. The *.zip are typically Windows binary
packages, pre-built. Some Windows users with programming experience do
build their own from source, the toolset is described in Appendix E of
the R Installation and Administration manual, and package installation
in Ch. 
6. If that isn't for you (or anybody nearby), say, and someone may have
a go at building a Windows binary. Whether it is worth the trouble for
spatial objects will however depend on the objects you want to make
clickable, if they are simple, it'll work, but if they are polygons with
very detailed boundaries (remember that the image map is raster while
the boundaries are vector), it may not scale well. Probably worth
trying, though.

Roger

Thanks,
matt

-----Original Message-----
From: Roger Bivand [mailto:Roger.Bivand at nhh.no]
Sent: Thursday, October 19, 2006 11:14 AM
To: Pettis, Matthew (TLR Corp)
Cc: r-sig-geo at stat.math.ethz.ch
Subject: RE: [R-sig-Geo] shapefiles, images, iimagemaps, and 
removinginternalboundary lines

On Thu, 19 Oct 2006 matt.pettis at thomson.com wrote:

Hi Roger,

Thanks again for the response.  To answer your questions:

- I am currently running on R 2.3.1.  I was at 2.4.x, but some of 
the packages I thought I needed weren't available on the cran 
interface in

the rgui (I was experimenting, and I can't remember what they were 
now, so that may no longer be true).  It sounds like you are fine 
running R at 2.4, though, and I could probably upgrade, as my sole 
purpose for having R right now is to deal with shapefiles and create
image maps.
- Related to the above, I don't see the spgpc package on my mirror 
(USA (IA)), but that may be related to being at 2.3?
No, but it isn't on CRAN, only on the little sp extras repository on
sourceforge:

rSpatial <- "http://r-spatial.sourceforge.net/R"
install.packages("spgpc", repos=rSpatial)

so this should install it. In fact there isn't yet a Windows binary 
for 2.4, so 2.3 is OK.

Also, I saw the 'unionSpatialPolygons' command in Debarchana Ghosh's

code, but didn't know what it did.  I'll investigate the paths you 
have listed here.

Thanks again,
Matt

-----Original Message-----
From: Roger Bivand [mailto:Roger.Bivand at nhh.no]
Sent: Thursday, October 19, 2006 2:32 AM
To: Pettis, Matthew (TLR Corp)
Cc: r-sig-geo at stat.math.ethz.ch
Subject: Re: [R-sig-Geo] shapefiles, images, iimagemaps, and 
removing internalboundary lines

On Wed, 18 Oct 2006 matt.pettis at thomson.com wrote:

I have sucessfully inputted a shapefile into a 
SpatialPolygonsDataFrame object.  I would like to output this file

as a .gif/.png/.bmp/.jpeg image and generate an imagemap for the 
outputted image.  Does anybody know the best way to approach this?
RSiteSearch("imagemap")

gets you to:

http://finzi.psych.upenn.edu/R/Rhelp02a/archive/28035.html

This installs on R 2.4.0 from source - which platform are you using 
and can you install source packages? The documentation in 
imagemap/inst/doc/imagemap-howto.pdf is clear, addRegion(im) <- for 
each clickable object. How to go from there depends on what you want

to be clickable.

Alternatives might be Rpad:

http://finzi.psych.upenn.edu/R/Rhelp02a/archive/77952.html

or using ogr2ogr in FWTools (external software) to generate a KML 
for Google Earth (if the bubble that pops up is enough - I don't 
know how to put a link into it, though I guess it could be done), or

writing the KML from R:

http://bbs.keyhole.com/ubb/showflat.php/Cat/0/Number/221682/Main/219
13
1

 secondly (and i may need to start another thread for this), but 
is there an easy function to remove the interior lines of 
aggregated shapes (and generate an imagemap again, etc.)?  For 
example, If I have

a map of the U.S.'s with a polygon for each state, could I remove 
all internal state boundaries to leave just the national border?
Using the objects you have now, you need to install the spgpc
package:
rSpatial <- "http://r-spatial.sourceforge.net/R"
install.packages("spgpc", repos=rSpatial)

and install gpclib from CRAN. Then

?unionSpatialPolygons

to dissolve internal boundaries. This is for arbitrary polygons, if 
you really just need to dissolve US states, perhaps using the CRAN 
maps package with its built-in database, and its own dissolve 
mechanism would save re-doing topology, but it only works for 
polygons
in the database.
Roger

thanks,
Matt

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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: Roger.Bivand at nhh.no

--
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: Roger.Bivand at nhh.no

--
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: Roger.Bivand at nhh.no

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: Roger.Bivand at nhh.no

shapefiles, images, iimagemaps, and removinginternalboundarylines

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