A Year-long Timelapse

January 02, 2009 at 12:00 PM in: time

Here's a nice year-longtimelapse for the new year. You may prefer to watch it in high-def.

One technique I haven't seen before is the use of tone mapping to prepare each frame. Tone mapping is usually used to compress high dynamic range images so that they can be displayed on a standard computer monitor. You can't show the the absolute brightnesses in an HDR image, but through tone mapping you can preserve the relative brightnesses.

For timelapse purposes, what tone mapping does is hide some of the variation in lighting conditions between frames. This means that you don't get unpleasant flickering in the video when a dim, cloudy day is followed by a bright sunny day. Shadows still appear and disappear across frames, but this is a clever way to preserve the same overall brightness.

Turin, Sanchez, Burr, and Gilbert

December 17, 2008 at 12:00 PM in: smell, perfume

Maybe I'm just late to the party, but the current interest in scent seems to trace back to a single individual: Luca Turin.  It started when Turin and Tania Sanchez wrote a book of inscrutable but hilarious perfume reviews. Chandler Burr then wrote a book about Turin and Turin's controversial theory about the mechanism of smell, and parlayed that into a job as the first ever perfume critic for the New York Times.

In response, Avery Gilbert wrote a less than complimentary review (pdf) of Burr's book and Turin's science, which led to a full-length book about the science of smell. Gilbert is occasionally pedantic - there are twelve pages devoted to debunking Proust and his fans. But What the Nose Knows is - title notwithstanding - the best popular science book on scent that I've read so far, if you're interested in the experimental evidence anyway.

Now, a fast-food chain is running a viral marketing campaign using perfume as the hook, and Dr. Gilbert has taken the opportunity to write a snarky Burr/Turin/Sanchez style review of Eau de Hamburger. Excerpt:

Flame's topnote unfolds like a prepubescent Asian contortionist climbing out of a crate of overripe Algerian pears. The bold viande accord in the heart introduces itself with solid, yet suave confidence - it's Richard Gere on steroids. Boisdur delivers a signature touch wtih a trace of instantly recognizable isopropylparabenzyldicaproic acetate. The effect is stunning: like spare ribs slow-cooking on a Weber E-210 at a Section C tailgate party in the Meadowlands. The drydown is long and satisfying.

Fifteen years ago the only book I found on smell was Max Lake's somewhat lascivious Scents and Sensuality, which was interesting but not exactly confidence-inspiring. Good times for olfactory aficionados - thank you Dr. Turin.

Aspen Palette

November 24, 2008 at 12:00 PM in: color, photos
Aspen Palette - Lake Sabrina, September 24 2008

Aspen Palette - Lake Sabrina, September 24 2008

Leaves collected near Lake Sabrina in the Eastern Sierras (at about 9200' elevation). Arrangement inspired by Andy Goldsworthy, of course.

The orange/peach colored leaves are new to me - in Colorado and New Mexico I've only seen the golden yellows.

Guidance for next year: California Fall color reports - Fall color updates for the Eastern Sierras

Using Git to sync a website

November 24, 2008 at 12:00 PM in: software

Git is an extremely powerful tool for file sharing and version control. Unfortunately it is too flexible for most uses - you need to construct a workflow for your particular usecase, and if you screw things up you may need an expert to help you recover.

I decided that Git was the right tool for maintaining nixweb.com, and ran straight into an undocumented use case.  So here I describe the setup and workflow I use for the site, in the hope that it may be useful to somebody. I assume basic familiarity with Git and Ssh.

The basic setup is that I have two "non-bare" repositories, one for the live nixweb.com site and one for development at home. My home machine is behind a firewall, so I need to use git-push to move changes to the live site after they are tested.

The obvious thing to do would be to push from my local master branch to the site's master branch. Unfortunately, this operation will screw up the repository on the live site, and you will have to find a Git expert to help you recover. The people who develop Git are aware of this problem but do not plan to fix it, which is one example of why Git is not ready for production use unless you have an expert on staff.

The only safe way to push to a "non-bare" repository is hinted at by Junio Hamano in an email message. You need to use git-push to transfer the changes from the home repository to a "remote" branch on the production website, then do a separate git-merge on the site to merge the changes into the live tree.

Here's how I set up the live site and home development site. All commands below are executed on the home (development) machine.

First, set up some variables that will be used frequently:

    # $remoteacct is your account on the production website.
    remoteacct=REMOTEUSER@REMOTEHOST
    # $homesite is the path to the development copy of
    # the site on the local machine
    homesite=~/testsite
    # Now test that ssh and git work on the remote machine.
    # This command may not print anything but it should succeed before
    # going any further.
    ssh $remoteacct git config --list

Now, initialize the remote git repository.  Here I assume it's in ~/public_html on REMOTEHOST.  You probably want hide the ~/public_html/.git directory using .htaccess too:

    ssh $remoteacct 'cd ~/public_html; git init ; git add .'
    ssh $remoteacct 'git commit -a -m "initial contents"'

Create the development repository by cloning the site to your home machine.  This git-clone command also creates the remotes/site branch on the home machine to track the state of the production repository, and populates the development area with a copy of the live site. Usually the branch would be called remotes/origin, but since we're usually going to be pushing rather than pulling, the name "site" is less ambiguous:

    git clone --origin site ssh://$remoteacct/~/public_html $homesite

Here's the unusual step: add a git-config option to allow git-push to work from the home master to the live site's remotes/home area, in addition to the pull setup created by cloning. Note that "site" in the command corresponds to "--origin site" in the git-clone command:

    cd $homesite
    git config remote.site.push '+refs/heads/:refs/remotes/home/'
    git push site

Now, whenever you need to update the site, you can use git-push to send the latest home commits to the remotes/home branch on the live site, and run git-merge on the live site to bring the changes online. The "home" in the git-merge matches the remotes/home in the git-config command above:

    git commit -a -m "commit updates in development area"'
    git push site
    ssh $remoteacct 'cd public_html ; git merge home/master'

To bring changes from the live site to the home repository, they must first be committed on the live site using git-commit. Then use git-pull to fetch the committed changes and merge them into the checked out home repository. You don't have to name the remote branch to use in git-pull because it is remembered from "git-clone --origin site ...".

    ssh $remoteacct 'cd public_html ; git commit -a -m "commit live site"'
    git pull

That's it! Use at your own risk - I'm not a Git expert at this point, but so far it's working for me.

Leslie Shows

November 17, 2008 at 12:00 PM in: geology, artists

I recently learned about San Francisco artist Leslie Shows, and went to check out some of her work at the Bay Area Now 5 show at YBCA.

The Arrangement of Salts and Metals by Properties - 48”x 72”, collage & acrylic on wood, 2005

Leslie Shows: The Arrangement of Salts and Metals by Properties

48"x 72", collage & acrylic on wood, 2005

Her work is largely inspired by natural landscapes - mountains and lakes, clouds, icebergs. The landscapes often suggest the impact of human exploitation - unnaturally flat rock faces or terraces hinting at quarries, streaks of lurid color in the waters reminiscent of mine tailings. Mixed in with the ink and paint there may be cutouts of gold jewelry or other extracted wealth. Lots of detail, very much worth seeing in person.

Apparently she grew up in Alaska.

Oddly enough the images that got me interested in this local-to-me artist came from London blogger Rodcorp. More of Ms. Shows's work is showing at Headlands Center for the Arts in Marin, until December 7 2008.

Welcome to Nixfeed

November 14, 2008 at 12:00 PM in: meta

As part of the site redesign for nixweb.com (formerly nixfiles.com), I'm starting a blog.  As far as I can tell, the advantage of the blog format is that it sorts everything by time.  So, feed.nixweb.com is for repeat visitors, while nixweb.com is for people who are just curious.

This is an experiment. I might as well admit that I don't know what I'll be posting here.

Comments are turned off for the time being.

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