Archive for December, 2006

Before the end of the year of dog

Tuesday, December 26th, 2006

The year of pig (hog?) is coming. Always, we are asked to make a schedule and a wrap-up, particularly, as detaily as possible. At the end of this year, there are a lot of things I have to do, want to do, and shouldn’t do.

    First of all, before going back home, I ought to finish my tasks:

  • 1) A report about the research advance in detecting the vegetation change (land cover change), especially the algorithms;
  • 2) Making an improvement in the existing System Dynamics Model, focusing on the water part.
  • 3) At last, a report about the land cover change in the northern China based on the SPOT/VEGETATION data. As they are all tough works, what I should do is calming down to delicate to complete them with cautions.

Secondly, what I should have had to do, but not yet, is present my sincere appreciations to all my friends remembering me. May be the list is too long, or omitting someone really important. I hope the answer is no.

  • 1) tsing send me such an expensive birthdaygift that I doubt I am still in a dream. It’s a two-year flickr pro account worth $48 (although I madly bear a half);
  • 2) Several Books coming from university classmates: “Noch Mal Leben Vor Dem Tod” (Germany, meaning “Portray of Life” in English) from Xi Tang; “Chun-Lao-Ji” (In Chinese, “Prose Collection: Spring Rice Wine“) from Rainbow. 3) three detective stories written by my favorite detective author – Agatha Christie: “The Hole“, ” The Murder of Roger Ackroyd“, “Death in the Clouds” from cc with a gorgeous packaging selected by Baozi.
  • 3) Cards designed by Stanley
  • 黄庆旭b黄庆旭a

  • 4) Dunhill perfume – Blue Desire from someone abroad and postcards from UK by Alexqiang.

At last, it’s very busy at the end of this semester. Homework occupy a lot of time, and the spare time is shared by secretary work. As I am getting used to these jobs, I should turn my gravity to the research field, such as:

  • 1) English Learning for the GRE and TOEFL tests
  • 2) Data Mining Methods
  • 3) Digital Imagery Processing
  • 4) Programming Learning — IDL

May the aims achieved next year. May everyone fit and healthy! Don’t hesitate to make a progress.

Merry Christmas

Saturday, December 23rd, 2006

Merry Christmas and Happy Coming Birthday!
This card is from IHDP.

Some news about 3S technology

Wednesday, December 20th, 2006

Near the end of this year, I heard of a lot of astonishing news from different channels.

1. An excellent site was introduced by tsing. For sharing remote sensing images, geoTorrent aims at distributing, what it claims to be legal, Satellite images and geospatial data, something that would be impossible over HTTP considering file sizes can go up to 87 GB.

2. Following two news come from Google. The first is that google has purchased Endoxon, an Internet mapping solutions company based in Lucerne, Switzerland. Second, Google has announced that its agreement with NASA on a variety of challenging technical problems ranging from large-scale data management and massively distributed computing, to human-computer interfaces. Google put more and more attention on google Earth and google Map. It’s a obvious sign and good opportunity for the colleagues working on geography.

3. As we know, SPOT data is very important in scientific research for its free of charge. VITO will be the unique distributor of VEGETATION products worldwide next year. Gladly, there are some improvements of deliver time, and no changes of initial digital image processing.

By the way, my paper has been printed by Acta Geographica Sinaca. Moreover, please looking forward my summary of this year.

Plus, Big Bird, thank you very much for persuading me to give up the stupid idea at the first time.

奥卡姆的剃刀原理

Wednesday, December 13th, 2006

做模型的时候要很注意的一件事情,虽然看起来很简单。同时,KISS(Keep It Simple Stupid)更容易记忆。以下内容转自Principia Cybernetica Web

Occam’s Razor

one should not increase, beyond what is necessary, the number of entities required to explain anything

Occam’s razor is a logical principle attributed to the mediaeval philosopher William of Occam (or Ockham). The principle states that one should not make more assumptions than the minimum needed. This principle is often called the principle of parsimony. It underlies all scientific modelling and theory building. It admonishes us to choose from a set of otherwise equivalent models of a given phenomenon the simplest one. In any given model, Occam’s razor helps us to “shave off” those concepts, variables or constructs that are not really needed to explain the phenomenon. By doing that, developing the model will become much easier, and there is less chance of introducing inconsistencies, ambiguities and redundancies.

Though the principle may seem rather trivial, it is essential for model building because of what is known as the “underdetermination of theories by data”. For a given set of observations or data, there is always an infinite number of possible models explaining those same data. This is because a model normally represents an infinite number of possible cases, of which the observed cases are only a finite subset. The non-observed cases are inferred by postulating general rules covering both actual and potential observations.

For example, through two data points in a diagram you can always draw a straight line, and induce that all further observations will lie on that line. However, you could also draw an infinite variety of the most complicated curves passing through those same two points, and these curves would fit the empirical data just as well. Only Occam’s razor would in this case guide you in choosing the “straight” (i.e. linear) relation as best candidate model. A similar reasoning can be made for n data points lying in any kind of distribution.

Occam’s razor is especially important for universal models such as the ones developed in General Systems Theory, mathematics or philosophy, because there the subject domain is of an unlimited complexity. If one starts with too complicated foundations for a theory that potentially encompasses the universe, the chances of getting any manageable model are very slim indeed. Moreover, the principle is sometimes the only remaining guideline when entering domains of such a high level of abstraction that no concrete tests or observations can decide between rival models. In mathematical modelling of systems, the principle can be made more concrete in the form of the principle of uncertainty maximization: from your data, induce that model which minimizes the number of additional assumptions.

This principle is part of epistemology, and can be motivated by the requirement of maximal simplicity of cognitive models. However, its significance might be extended to metaphysics if it is interpreted as saying that simpler models are more likely to be correct than complex ones, in other words, that “nature” prefers simplicity.

非人类

Thursday, December 7th, 2006

Schedule,Reply-mail,Digital Image Interpretation,Classes,973 projects

等我冲回宿舍,已经是10:30,接近洗澡的Deadline,我还是冲进去了,几分钟之后发现跟大澡堂不一样,热水变温水、水量也在变小。我预感大限到了……但是怎么处理那些还在我身上和头上的泡沫啊……出来之后(头发还没有冲,我果断地决定上去再洗头)发现没有带门钥匙,但是我已经上了电梯……这一切的一切都可以写进糗事百科了。

还需要做图到现在:
vegetation_cover_in_spring

vegetation_cover_in_summer

vegetation_variation

植被变化监测

Wednesday, December 6th, 2006

Erdas、ENVI、Arcgis用起来还是非常可爱的,我好喜欢它们,特别是它们神奇地实现了我的设想之下。最大值合成法、混合像元模型、变化矢量监测、图像假彩色密度分割。越往后面越知道会编程,会制作自己的模型,才是王道。下面是一些暂时的“成果”,hoho

vegetation_change_detection in spring from 1999 to 2005

vegetation_change_detection in summer from 1999 to 2005