I’ve spent a fair amount of time over the last month re-doing three web sites:

Some of it, like the PostGIS site, has been easy, simply re-skinning the existing content (though I’m anticipating reworking the content there to make it more newbie friendly and harmonized). Other bits, like the uDig site, are brand new, and include some big additions like a gallery of projects using uDig. And the Refractions site includes piles of new content like case studies, that have taken many days to write up. And I’m only about 50% through my list of candidates.

PostGIS users will find this nugget in the Refractions site fun: a potted history of PostGIS.

Timmy's Telethon #0

In the comment thread at James Fee’s posting on building an open source application in an “ESRI” shop, “timmy” provides the most complete laundry list of incumbent vendor objections to open source I have seen in some time.

The list is far too comprehensive to do in one post, so I’ll do them one at a time.

As a general note, many of the items are not really specific to open source or geo-spatial – they could be used by any incumbent market-leading vendor to attack a smaller competitor.

There is also an apples/oranges thing going on here, since the default GIS vendor (ESRI) is at a different point in the technology adoption cycle than open source. Open source can’t strongly appeal (yet) to conservative late adopters, and ESRI is finding it hard (at the moment) to appeal to technically savvy early adopters. (Technology book recommendation: Crossing the Chasm is a must-read for anything thinking about the software market.)


I’ve always like ImageMagick, and frequently it is the first thing I install when I set up a new computer. For OS/X, I have found that MacPorts make the installation pretty painless, although it takes a while to compile all the dependencies.

Like most ImageMagick users, I have rarely scratched the surface of what this toolkit can do – I mostly use it for simple format conversions and image re-scaling. However, I recently had a image processing problem that went beyond the ordinary – I wanted a general purpose tool that would take any input image, scale it to 200 pixels wide, and create nice rounded corners, with transparency where the pixels used to be.

Basically, to go from this:

To this:

Since I plan on doing this a lot, I don’t want to fire up a graphics program every time and point-and-click my way to nirvana. Enter ImageMagick, my old friend!


# Usage:
# ./roundclip.sh [inputfile]

# Output width
# Corner size

BASE=`basename $IMG .$EXT`

# Scale the input down to our desired width
convert $IMG -scale ${OUTPUTWIDTH}x $TMPFILE1

# Find out the height and width of the working file
DIM=`identify -format %wx%h $TMPFILE1`
W=`identify -format %w $TMPFILE1`
H=`identify -format %h $TMPFILE1`

# Calculate the lower corner coordinates
X=$(($W - 1))
Y=$(($H - 1))

# Make a clipping mask with rounded corners
convert -size $DIM xc:black \
    -fill white \
    -draw "RoundRectangle 0,0 $X,$Y, $CSIZE,$CSIZE" \

# Make a transparent underlay
convert -size $DIM xc:transparent $TRANSPARENT

# Place the masked input image onto the transparent underlay
composite -compose src-over $TMPFILE1 $TRANSPARENT $MASK $TMPFILE2

# Convert to the output format, and do some color reduction
convert $TMPFILE2 -quality 90% $OUTFILE

# Clean up the temporary files

There are probably much more efficient ways to do this, with fewer intermediate steps, but I am not a guru yet.

Using other drawing and blurring techniques, it’s also possible to create drop-shadows on the fly too…

Transparent PNG for IE6

I’ve been wrapping our web content in some new web designs, and one of the issues I have encountered is supporting transparent PNG on IE6. It can be done, and all it requires is a relatively unobtrusive hack that uses the IE-only “behavior” CSS attribute.

Stangely, though, while our web developer could serve pages that worked with this trick, when I implemented them on our own servers, it didn’t work! It took a while to realize that the problem wasn’t how I was implementing the hack (“check the URLs”, “are you line stripping the files?”, “make sure the files aren’t missing”) but rather from where I was serving the hack. Namely, from an old server running Apache.

IE6 would not execute the hack, which was bundled in an IE-only “behavior” file, with a .htc extension. It would load it, I could see that in the logs, but it never did anything. The problem was that my old Apache wasn’t serving up the .htc file with the mime-type that IE wanted on it.

So, one quick entry in /etc/mime.types and an Apache restart later:

text/x-component htc

And we’re golden.

Chemistry Change

I am a sucker for catastrophe, so I am fortunate to live in this age of (as the Chinese might say) “opportunity”. We are privileged to be witness to the twin cataclysms of peak oil and global warming. It may not have the immediacy and drama of the sack of Rome but, baby, it’s got size.

In the past year, I finally got to see “An Inconvenient Truth”, which really is worth seeing, even if you know all about global warming already, because it is such a clean compendium of all the issues, scientific, political, cultural, that we are navigating on our way into this crisis. It brings everything into a neat package, tied with a bow, a truly great work of documentary film making.

However, the real eye-opener for me in the last year was an under-appreciated article in the New Yorker, “The Darkening Sea” by Elizabeth Kolbert. The gist of the article is that by changing atmospheric chemistry (by injecting CO2 in higher concentrations) we are also changing oceanic chemistry (as the oceans absorb the extra CO2). The eye-opener is just how deep through the ecosystem this change in ocean chemistry reaches. I cannot recommend this article highly enough, it’s one of the best of the last couple years.