Tuesday, November 29, 2005

Stroboscopic snowflakes?

When I first came to Canada in 2000 I was living in Ottawa, so I got to see a lot of snow. Being from Australia I was fascinated by the snow. Less so about the ice and the minus 35 degrees, but the snow was almost magical.

Growing up in Geelong it never snowed, although I do remember once when there was a hail storm that dumped about 2cm of hail on the ground that I could pretend it was snow. But I was 19 before I experienced my first clump of snow on the side of the road driving through a National park in Victoria (AUS).

Now that I'm living in Vancouver (BC), snow happens much less frequently than in Ontario. But I'm still intrigued and fascinated by it.

Last night about 5cm of snow fell. I stood out on the balcony of our apartment and watched it fall. Watched it twist and move in the wind. It wasn't too long before I set up my camera to take some photos. It seemed like the thing to do.

There is a street lamp a few metres from the balcony and I wanted to use a long time exposure, in order to capture the dance of the snowflakes as they fell. When I went through the photos tonight, I noticed something that intrigued me. In the images where the snow was falling fast, so the flakes were captured as long streaks on the image, there was a regular variation in the brightness along the length of the streaks.

Canon 300D, 70-200mm f4L lens @ f5.6 + 0.5 seconds + ISO 400

But in the images where the flakes were not moving in such a fast and uniform motion, there wasn't any hint of the banding on the streaks.

Canon 300D, 70-200mm f4L lens @ f5.6 + 0.5 seconds + ISO 400

And this is another example where some of the streaks show banding and others don't appear to:


Canon 300D, 70-200mm f4L lens @ f5.6 + 0.5 seconds + ISO 400

I captured a lot of images last night and many of the images show this effect, it is remarkably consistent. One thing I do know is that it isn't caused by the snow flakes tumbling and varying in brightness across the frame. In fact it is always the opposite effect. The banding only occurs in those images where the snow was moving rapidly across the image.

I can only summise that it is caused by some sort of strobe effect from the sodium street lamp. Although I haven't been able to find any reference to this on-line. Although I may have used the wrong search terms.

Here are a couple of other images showing the banding effect - the street light illuminating the flakes is just above the upper left corner of these shots:

Canon 300D, 70-200mm f4L lens @ f5.6 + 0.5 seconds + ISO 400

Canon 300D, 70-200mm f4L lens @ f5.6 + 0.5 seconds + ISO 400

Can anyone confirm the mechanism that causes this intriguing effect?

Monday, November 28, 2005

The fountains of Enceladus

The Cassini space probe has snapped some fascinating images of fountains of particles streaming into space from Saturn's moon Enceladus. The image below shows the streams of material illuminated by sunlight from behind the moon... A false colour image shows more details of the phenomenon.

Ever since the Tiger Stripes seen near the Southern pole of the moon were found to be warmer than the surrounding landscape, it has been suspected that some form of ice volcano may be pushing material out the Tiger Stripes. Now we now that the effect is real and we can add another body in the solar system to the list of geologically active worlds. Cool!

Sunday, November 27, 2005

Mount St Helens update

The last week has been both interesting and frustrating. Interesting because there have been several nights when the weather has been clear and the glow from the lavadome has been visible. Frustrating, because the focus of the Volcanocam is still not correct and won't be for another week or so.

The focus of the Volcanocam was knocked out of whack on the 9th November when the maintenance crew fixed the power problem to the camera. Unfortunately, at this time of year it is not a simple matter to drive up to JRO and fix the problem and the problem with the focus of the camera wasn't apparent when the crew performed the original repairs.

What is worse from the night time image perspective is that the focus was knocked out even further for the near-IR response of the camera, compared to the daylight view.

I have tried various means of processing the Volcanocam images to compensate for the problem, but deconvolution is not a simple solution. Without knowing the exact nature of the focus problem, you have to use generic solutions. This means that the solution may not accurately compensate the problem.

The most success I have had is using maximum entropy deconvolution. The following is an example of the current state of night time images from the Volcanocam, and this is what I have been able to extract using deconvolution. It does look similar to the night time images from previous nights, but the best solution will only come from the maintenance people being able to get back to the camera and correct the problem manually.

Here's hoping they will be able to get back up to JRO and fix the problem sooner rather than later...

Tuesday, November 22, 2005

Microsoft patents web photo gallery software

Microsoft has been awarded a US patent (US #6,964,025) for software which enables a user to easily and automatically create a photo gallery of thumbnail images on a Web page. This is further explained to mean that a user selects a group of original images, and the tool automatically produces a corresponding group of thumbnail images on the Web page, with hyperlinks to the corresponding original images.

Now this doesn't exactly sound like rocket science to me. The patent goes on to detail the selection of images, creation, cropping, rotation and linking of thumbnails to the larger original sized image, displaying a preview of the webpage and many other options that are freely available in many freeware, shareware and commercial programs designed to simplify the creation of web photo galleries.

Now according to Microsoft, when creating Web pages, especially Web pages that incorporate a considerable amount of content such as thumbnail images hyperlinked to original parent images, the file management and structural organization required can be challenging, particularly for the casual user.

Clearly, it would be desirable to enable a plurality of images to be incorporated into a Web page as thumbnail images in a single operation, rather than requiring each image to be added individually through a series of manual steps, or even as an automated process that must be repeated for each image. It would also be desirable to provide a plurality of user-friendly templates that automatically define several different formats for a plurality of thumbnail images on a Web page, so that a casual user can easily create an aesthetically-pleasing gallery of thumbnail images with a minimum of effort.

Interestingly, they go on to claim that the prior art does not teach or suggest such a tool.

The term prior art is patent speak for what exists in the public domain. Now admittedly the patent application was filed on March 20, 2001, but can this really be a serious patent and what are the implications for all of the existing web photo gallery creation software out there? Is Microsoft about to start demanding royalties from every program that automatically create a photo gallery of thumbnail images on a Web page?

Sunday, November 13, 2005

Unjust corporate intimidation of a concerned mother

Louisette Lanteigne of Waterloo, Ontario, was concerned about the environmental and human costs of the development in her local area caused by the property developer Activa Holdings Inc. She studiously recorded environmental and EHS violations by Activa, even winning accolades from the provincial authorities for her efforts.

Now Activa Holdings are suing this concerned single mother for $2 million for libel.

This is obviously nothing more than a SLAPP suit - a legal action intended to intimidate the recipient into submission.

After reading through the information that Louisette Lanteigne has compiled I don't see anything that deserves a $2 million law suit. I do see a mother that is concerned about her children and her community. I also see a corporate entity that has far too much money at its disposal and no consideration of ethics in its behaviour.

Activa Holdings Inc, is not a publicly listed company in Canada, as evidenced by a search for their name on SEDAR. This story was recently posted on Slashdot, and some of the responses helped to pinpoint the people behind this law suit.

If you felt their behaviour was unacceptable I would encourage you to send them and e-mail expressing your outrage that they would try such legal BS against a single mother, who did little more than report their own environmental and EHS failures. This is not an attitude or response you would expect from a responsible company.

A first point of contact would be:

Peter Armbruster
Activa Group
735 Bridge Street West
Waterloo, ON N2V 2H1
Phone: (519) 886-9400, Ext 104
Fax: (519) 886-8955
E-mail: parmbruster@activagroup.ca


Mount St Helens - update 13 November 2005

Well, another week without much activity on the mountain. The week began with a glitch in the Volcanocam causing the images to appear a featureless blue. This turned out to be a blown fuse in the power supply feeding the camera.

A good thing the system worked by blowing the fuse rather than the camera! It was repaired on Wednesday by the maintenance crew and pictures started to flow back to the server. Unfortunately, during the repairs, the focus on the camera was slightly changed, leading to slightly out of focus images during the day, and very diffuse images of the glow at night.

The US Forest Service have scheduled another maintenance trip for this week to adjust the focus. Although the weather has been so bad that there hasn't been much to see at night or during the day. The weather forecast for the next week looks a little more promising, so here's hoping that the weather gives us some good views of the crater at night this week.

On the morning of 12 November 2005, the clouds parted to reveal icicles nicely framing the view of the crater. Not an eruption, but pretty nonetheless...

Sunday, November 06, 2005

Mount St Helens update

The views of the crater from the Volcanocam have been obscured by clouds almost every day this week, so there is little to report on the night time activity from the mountain. Last night at 18:43 the Volcanocam stopped tranmitting images from the mountain and since has only been showing featureless blue images, reminiscent of the BSOD (Blue Screen of Death), which should be familiar to most Microsoft Windows users... hopefully this is just a temporary glitch and not a sign of a more fundamental problem with the camera.

The USGS recently posted an interesting image comparing the current view of the crater with those from November 29, 2004, February 22, 2005, June 21, 2005, and August 31, 2005 (shown below). The growth of the new lavadome continues unabated, with the most recent figures showing that the volume had grown to 62 million cubic meters (81 million cubic yards) at an average rate of growth during late July and early August of about 2 cubic meters per second.

USGS photograph taken on October 30, 2005, by John Pallister

There is also a new mosaic of images of the growing lavadome taken over the last year from the Sugarbowl. The Sugar Bowl Dome is located at the crater mouth about 2.3 km (1.4 miles) north-northeast of the vent.



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