Fun with aerial photography

Work has just been crazy and non-stop, a lot of it involving aerial photography ‘orthorectifying’. What that basically means is that I have a set of aerial photos that I am ‘stitching’ to an existing, known co-ordinate framework. This process is undertaken in a program called ArcMap, which is a GIS (Geographic Information System) style program.

Brisbane City Council have provided me with aerial photography for their entire council area. Not only is this a huge area (Brisbane City Council is the largest metropolitan council in Australia), but the resolution of the imagery is 15cm! This means that each pixel is 15cm x 15cm, allowing a detailed assessment of habitat at an amazing resolution! See this example image that is of our new place, which is the !

There are three main ways that aerial photography is provided; all of which vary in their degree of work required to produce a final photo array and all of which vary in their eventual accuracy.

1) A third of all photos are already orthorectified when I receive them; Brisbane City Council’s photos (thankfully) fall into this category. What this means is that I open them, and they fit nicely onto a map with their spatial co-ordinates accurately presented.

2) Then, almost two thirds of aerial photos are static images that I have to stitch to the framework myself, although luckily this sort of photo has an additional ‘tab’ file that states what the SW, NW, NE and SE co-ordinates of the photo are. You then instruct the program to move the corners of the photos to the given spatial co-ordinates. This is still a very time-consuming exercise, and the other day, I spent over 6 days (including a lot of weekend time) performing this exercise on 380 photos for the entire 1996 Gold Coast Council area…

3) The third way that aerial photography is provided is literally static images with no reference to where they belong. With these photos, you basically have to match a given image feature (i.e., road intersection, driveway-road intersection, building corner) with a known spatial co-ordinate. So for example, if I have an aerial photo of my neighbourhood, and I know (using my GPS unit) that the corner of my street is 27.607° S, 153.074° E, I designate that ‘control point’ on the aerial photo, as that known spatial co-ordinate. The more control points that you do this with, the more accurate your image will reflect reality. This process of ‘orthorectifying’ is also known as ‘rubber-sheeting’ once you have enough matching points on the photo. Through a process called ‘1st order polynomial’ and ‘2nd order polynomial’ transformations, parts of the aerial photo are effectively stretched and contracted to best match their true spatial location; thus the term ‘rubber-sheeting’. The image on the right shows what I mean, and comes from the ArcGIS help webpage. THIS method of orthorectifying is the most time consuming and inaccurate method, as the manipulation of the photo based on your control points is like laying a sheet over the ground and while you may be able to relatively accurately anchor parts of that sheet to the ground (control points), those parts of the sheet between the points are not necessarily where they should be. In the end, you can reduce the ‘error’ between the aerial photo and where you say those control points should be by just increasing the number of control points....... all depends on how accurate you need the data to be…

I have pasted below an interesting collection of photos from the Manly region of Brisbane. It shows a 2007 image (provided as a pre-orthorectified, according to the type 1 process as described above) image) of the region, and then a 1991 image (orthorectifying myself according to the type 3 process as described above), and finally a 1958 image that I managed to get my hands on and self orthorectify. It shows nicely the increase cover of development and reduced cover of native vegetation over 50 or so years! If you save them all and view them as a slideshow, you can see how you can accurately stitch photos on top of each other!

Interesting new rainfall model...

I came across a fascinating article published on http://www.weatherzone.com.au/. It outlines a talk to be presented at the Greenhouse 2009 conference, and later, published in the Geophysical Research Letters journal. It represents a model that can predict rainfall and associated risk of bushfires, especially in Victoria, based on the oceanic temperature difference between the western and eastern parts of the Indian Ocean! By all appearances, it looks like the model fits rainfall data somewhat better than the traditional El Nino/La Nina system, although it invariably interacts with it in the global oceanic ciculation model. It is pasted below.

A weather pattern centred on the Indian Ocean may provide an early warning system for major bushfires in southern Australia, climate experts say. Dr Wenju Cai and Tim Cowan, of CSIRO's marine and atmospheric research centre, have uncovered a link between the Indian Ocean Dipole (IOD) and Victoria's killer bushfires. Dr Cai will tell the Greenhouse 2009 conference today that 11 of 16 major bushfires in Victoria since 1950 have been preceded by what is known as a positive IOD event. He says an unprecedented three consecutive positive IOD events preceded February's devastating Black Saturday bushfires. The IOD refers to temperature fluctuations in the east and western Indian Ocean.


The picture of the left demonstrates change in the sea surface temperature between the western and eastern Indian Oceans (between month 0 and 12) which is apparently a very strong predictor for rainfall and potential bushfire threat patterns in Australia.

In its negative phase, the IOD brings cool water to the ocean west of Australia and warm water to the north, leading to winds that bring rain-bearing air over the continent. In the positive phase, water temperatures are reversed and less rainfall travels to Australia, particularly to Victoria where the negative IOD provides winter and spring rains. As part of their research, Dr Cai and Mr Cowan recorded changes in the IOD using Argo floats; robotic devices that measure the sub-surface ocean temperature.

They found the IOD was in an "unprecedented" positive state for three consecutive years leading up to 2009. They say this preconditioned the environment to the extent that it was almost inevitable the bushfires, which claimed more than 200 lives, would occur. "If you look at the accumulative soil moisture in Victoria, it's unprecedented, it's never been so dry," Dr Cai said.

The researchers also found an IOD link to the Ash Wednesday bushfires of February 1983, with a positive event reducing rainfall during the winter of 1982. Mr Cowan says of the 11 bushfires preceded by a positive IOD, six were coupled with an El Nino event. But, there was only one occasion where an El Nino alone preceded a bushfire, compared to the five times when only an IOD impacted on the rainfall. This shows the influence of the IOD was enough to precondition the environment to high bushfire risk, says Mr Cowan.

Dr Cai and Mr Cowan say climate change projections show the frequency of positive IOD events will increase in the future. "Almost all climate models say under climate change we are going to have an Indian Ocean warming pattern," Dr Cai said. "That means it has to be manifested in either more frequent positive IOD events or higher intensity positive IODs."

According to Dr Cai, the effects of climate change can already be seen. Between 1900 and 1930 there were four positive IOD events, he says. But in the past 30 years there have been 12 positive IODs, a 400 per cent increase. For Victorian residents living in bushfire-prone areas that is bad news. Dr Cai says the continued suppression of rainfall in Victoria will only make conditions more fire friendly. "The implication [of the research] is if we have a positive IOD in one year then the following season you have a higher bushfire risk," he said. According to Dr Cai this knowledge could provide an early warning system. "It gives us four to five months' lead time [to prepare for bushfires]," he said.

He says modelling shows that climate change will also lead to a 30 per cent increase in the number of consecutive events, while the odds of three consecutive IODs occurring increases by 300 per cent. "In 1,000 virtual years without climate change we get two occurrences [of three consecutive positive IOD events]. With climate change factored into the modelling this becomes eight."

The research is due to be published in a series of papers in the Geophysical Research Letters.

The synergistic environmental/economic crisis.

Haven't posted for a while, but I received an interesting email from a subscribed post-doc fellows email list here at Griffith Uni. It is an opinion piece by Thomas Friedman from the March 7th opinion pages of the New York Times. Thomas is a regular columnist with the New York Times and a Pulitzer Prize winning author. This article outlines the economical and ecological unsustainable outcome of the ubiquitous 'growth model' that we hear the politicians and business sectors so vehemently following. A great short article on what is so bleedingly obvious; consumerism and corporate greed spells synergistic environmental and economic collapse!

The Inflection Is Near?

By THOMAS L. FRIEDMAN
Published in The New York Times, March 7, 2009

Sometimes the satirical newspaper The Onion is so right on, I can’t resist quoting from it. Consider this faux article from June 2005 about America’s addiction to Chinese exports:

FENGHUA, China — Chen Hsien, an employee of Fenghua Ningbo Plastic Works Ltd., a plastics factory that manufactures lightweight household items for Western markets, expressed his disbelief Monday over the “sheer amount of [garbage] Americans will buy. Often, when we’re assigned a new order for, say, ‘salad shooters,’ I will say to myself, ‘There’s no way that anyone will ever buy these.’ ... One month later, we will receive an order for the same product, but three times the quantity. How can anyone have a need for such useless [garbage]? I hear that Americans can buy anything they want, and I believe it, judging from the things I’ve made for them,” Chen said. “And I also hear that, when they no longer want an item, they simply throw it away. So wasteful and contemptible.”

Let’s today step out of the normal boundaries of analysis of our economic crisis and ask a radical question: What if the crisis of 2008 represents something much more fundamental than a deep recession? What if it’s telling us that the whole growth model we created over the last 50 years is simply unsustainable economically and ecologically and that 2008 was when we hit the wall — when Mother Nature and the market both said: “No more.”

We have created a system for growth that depended on our building more and more stores to sell more and more stuff made in more and more factories in China, powered by more and more coal that would cause more and more climate change but earn China more and more dollars to buy more and more U.S. T-bills so America would have more and more money to build more and more stores and sell more and more stuff that would employ more and more Chinese ...

We can’t do this anymore.

“We created a way of raising standards of living that we can’t possibly pass on to our children,” said Joe Romm, a physicist and climate expert who writes the indispensable blog climateprogress.org. We have been getting rich by depleting all our natural stocks — water, hydrocarbons, forests, rivers, fish and arable land — and not by generating renewable flows.

“You can get this burst of wealth that we have created from this rapacious behavior,” added Romm. “But it has to collapse, unless adults stand up and say, ‘This is a Ponzi scheme. We have not generated real wealth, and we are destroying a livable climate ...’ Real wealth is something you can pass on in a way that others can enjoy.”

Over a billion people today suffer from water scarcity; deforestation in the tropics destroys an area the size of Greece every year — more than 25 million acres; more than half of the world’s fisheries are over-fished or fished at their limit.

“Just as a few lonely economists warned us we were living beyond our financial means and overdrawing our financial assets, scientists are warning us that we’re living beyond our ecological means and overdrawing our natural assets,” argues Glenn Prickett, senior vice president at Conservation International. But, he cautioned, as environmentalists have pointed out: “Mother Nature doesn’t do bailouts.”

One of those who has been warning me of this for a long time is Paul Gilding, the Australian environmental business expert. He has a name for this moment — when both Mother Nature and Father Greed have hit the wall at once — “The Great Disruption.”

“We are taking a system operating past its capacity and driving it faster and harder,” he wrote me. “No matter how wonderful the system is, the laws of physics and biology still apply.” We must have growth, but we must grow in a different way. For starters, economies need to transition to the concept of net-zero, whereby buildings, cars, factories and homes are designed not only to generate as much energy as they use but to be infinitely recyclable in as many parts as possible. Let’s grow by creating flows rather than plundering more stocks.

Gilding says he’s actually an optimist. So am I. People are already using this economic slowdown to retool and reorient economies. Germany, Britain, China and the U.S. have all used stimulus bills to make huge new investments in clean power. South Korea’s new national paradigm for development is called: “Low carbon, green growth.” Who knew? People are realizing we need more than incremental changes — and we’re seeing the first stirrings of growth in smarter, more efficient, more responsible ways.

In the meantime, says Gilding, take notes: “When we look back, 2008 will be a momentous year in human history. Our children and grandchildren will ask us, ‘What was it like? What were you doing when it started to fall apart? What did you think? What did you do?’ ” Often in the middle of something momentous, we can’t see its significance. But for me there is no doubt: 2008 will be the marker — the year when ‘The Great Disruption’ began.

Photos of Sydney Uni taken in Dec '08

In December, Rebecca and I went to Sydney for the Ecological Society of Australia conference that I was presenting at. I presented a poster entitled "How dynamic are forest and suburban bird communities?" which represents a very small part of my work here at Griffith University. Feel free to download a PDF copy of the poster by clicking here. The conference was held at Sydney University, a place of amazing history and architecture. I recently downloaded the photos from the camera and decided I would finally take the time to post some of the photos I took of the Quadrangle Building. You can link to them here on on the right in the Picture Albums section.

Climate change analogy

Yesterday, I was listening to an ABC Science Show podcast initially aired on Saturday 31st January 2009 and heard one of the best analogies regarding the need to halt the ever-present and accelerating climate change issue. It was a quote by John Holdren, Professor of Environment Policy at Harvard, who was selected as Assistant to the President for Science and Technology, and Director of the White House Office of Science and Technology Policy. Here is what he said...

"The current situation of the world in relation to the climate problem is that we're in a car with bad brakes driving toward a cliff in the fog, and the fog is the scientific uncertainty about the details that prevent us from knowing exactly where the cliff is. The climate change sceptics are telling us that the fog is a consolation and that we shouldn't worry because we're uncertain about the details, but of course any sane person driving a car toward a cliff in the fog and knowing that the brakes are bad, that it takes the car a long time to stop, will start putting on the brakes, trying to slow the car, without knowing exactly where the cliff is but just in the hope that by putting on the brakes we'll be in time to keep from going over the cliff. You don't have to be sure that you can still avoid going over the cliff to put on the brakes, you want to do it in any case. And that's what the world should be doing with respect to the emissions of greenhouse gases that are causing this climate problem. There's a chance we'll go over the cliff anyway but prudence requires that we try to stop the car."

GREAT analogy, in that it addresses the nay-sayers, as well as reinforces the need for action. It is great to finally see someone associated with the White House that has an obvious passion, but more importantly, the brains to deal with the impending issue that is climate change. Having said that however, from an academic point of view, I worry about the degree of influence that climate change appears to have in the scientific literature. For that, I will need to write another post, because there are a number of elements I wish to discuss, so will need to think about it first...

Rainfall and temperature of late...

The weather that we are experiencing at the moment throughout Australia is phenomenal. We have disaster relief programs brought on from flooding in the north of Queensland and the tragedy of fire in Victoria. I have pulled some data from the Bureau of Meteorology website that exemplifies the bizarre nature of the weather experienced this year already.

Rainfall
The rainfall data shows some very interesting trends throughout the country. Firstly, you can tell from the first figure the vast amount of rain that has fallen in northern Queensland. A quick check of some centres indicates some amazing facts. One of the wettest weather stations this year has been Hawkins Creek, just NW of Ingham, where since the start of the year, 2,694.2mm has been recorded, including 1376.8mm in the last 12 days! That yearly total to date represents over three times the annual average rainfall for Perth and over twice that of Sydney! Needless to say, with that much rain falling in the region, flooding is a major issue. Flooding has also gripped large parts of the western edge of Queensland from Burketown all the way down to Birdsville. The Diamantina, Gregory, Nicholson, Albert, Leichhardt, Flinders, Cloncurry, Norman and Gilbert Rivers, just to name a few, are all presently on flood watch; many of them have been on flood watch for almost a month. Note also the interesting rainfall pattern in Western Australia. There has been more rain falling in the arid interior of WA then there has been on the coast. No doubt, the pattern of rainfall from Port Hedland down to the Nullarbor was due to the passage of various rain-bearing depressions and Cyclone Dominic, although this pattern of elevated rainfall through the interior of WA is evident over the last 10 years or so, often independent of cyclone activity… interesting!! Note also on the map that much of the area devastated by the recent bushfires in Victoria have received little to no rainfall. Apparently, much of Victoria experienced a relatively wet December which helped to boost understorey vegetation. Following this, a very dry January and heatwave at the same time (see below) resulted in all this ‘fuel’ drying out.

The second figure I show is the percentage of yearly rainfall received to date. What is amazing on this figure is that as of the 11th February, much of northern Queensland has already received their average rainfall for the year, with some places in the Gulf country already having received over twice their average yearly rainfall already… and it is only the 11th February! If they don’t receive a single millimetre for the rest of the year, they would already have received twice their yearly rainfall. Unfortunately, there appears to be no end to the rainfall in the immediate future.

Temperature
As we have seen, the Victorian bushfires are unprecedented in the sense of ferocity, intensity and loss of life. What hasn’t helped has been the incredible temperatures experienced throughout the southern states in the last 2 months. On Saturday 7th February, the day the fires claimed so many lives, Melbourne experienced their hottest day in 151 years of records; 46.4 degrees, or 20.6 degrees above the January average! Add to this, temperatures of 36.4, 43.4, 44.3 and 45.1 between January 27th and 30th, and you have some strange weather! Likewise, at the same time, Adelaide sweltered through temperatures as high as 45.7 degrees, and for 13 days between Monday 26th January and 7th February, the temperature only dropped below 36 degrees on one day, and included 8 days over 40 degrees! The cause of much of this heat was the presence of a heat trough (shown as a dashed line) perched just to the west of Adelaide and Melbourne around the time of the heatwave, which was being held there by a high pressure system in the Tasman Sea, and brought hot dry winds from the NW over the parched, dry and hot inland. Any time you see a trough line to the west of where you are, expect hot weather, especially if it plants itself there for days! This is regularly seen in Perth, and you watch; those days they expect hot temperature, you can almost guarantee a trough just off the coast, and as soon as it passes, it dramatically cools down. On 8th January, the maximum temperature reached just 24.8 degrees compared to 41.5 degrees the day before. Likewise, on the 8th January in Melbourne, the temperature reached just 22.5 degrees compared to 46.4 degrees the day before; a 23.9 degree turnaround. That same trough line that brought this hot weather then cooked Sydney for an extra day as it moved east, bringing 42.5 degrees to Penrith, before dropping to 23.6 degrees on Monday.



The image I show here is the maximum temperature anomaly (that is, the differnce between that observed, and the long-term average) for both the month of January, as well as the last 7 days, which shows the uncharacteristically high maximum temperatures in the southeast of the country and the extraordinarily cooler maximum temperatures in the gulf country of northern Queensland, associated in part with all the rain they have received.

These patterns of temperature and rainfall have given rise to the current state of northern Queensland and their floods and the devastaing bushfires in Victoria. We can only hope that the coming months ease the burden on the people affected by these unsual weather events. Check out on the Bureau of Meteorology website, as well as the Weatherzone website, which you can register with to get really good weather information, outlooks as well as interesting weather news and facts! ENJOY!

Our veggie garden - Day 14

Well, the veggie garden has been growing for 14 days now (seedlings planted on the 18th Jan), and there have been mixed results. The basil has grown crazy, and we have used it in a variety of dishes from bolognese sauce to topping on pizza. The tomatoes and capsicum have not grown so much, and I suspect that they may be over-watered. Today, I bought some more seedlings as well as some wooden stakes to lay the growing containers over to keep them off the ground. This should help drainage. The other seedlings I bought were zucchini and spring onions. From a single punnet, I managed to tease apart well over 50 onions!!

I have to say, today's gardening was one of the most relaxing and therapeutic afternoons I have had in a very long time: the weather was coolish, overcast with a light wind. Now, there may be some out there that would suggest I should 'harden the fu*k up' and get with the 'pig-rooting' and 'chick-shooting' mentality or whatever it is :), but try it out!! You'd be surprised! There is something very satisfying about not only watching things grow, but harvesting your own food!!

I will post the photos of the other seedlings and the new setup soon....... and the house photos..... hopefully even sooner.....