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Is The Great Wall Visible From Space - An Aerial Survey with Google Earth

There is a saying that the Great Wall of China, an earthen fortifications stretching more than 6000km, is the only human-made structure visible from space. Is this a true claim? Unfortunately space tourism has not arrived yet, so we cannot fly over to verify it. But the next best thing, the Google Earth, is already here for free. Better yet, anyone can do an aerial survey simply from a home computer.

Let's go to Badaling(八達嶺), a mountain pass north of Beijing where all the tourists flock to see the restored section of the Great Wall. I have captured three pictures from altitude of 1km, 12km and 100km.

From the 1km picture, you can clearly see the wall and two square towers. The next picture is from 12km above, the cruising altitude of a 747 plane. The gray dot at the center is the park's entrance and a parking lot. The curvy line going from the lower side to upper left is a highway, not the Great Wall! If you look really carefully you can spot the Great Wall as a faint line along the ridge running from the lower left side to upper right side through the visitor's entrance. The Great Wall is already hardly visible from a 747.

Moving on to the third picture from 100km above, not quite from the space yet but from a low earth orbit. Not a trace of the wall nor the visitor's center is visible. The grayish area at the lower right hand corner is part of the Beijing metropolitan.

For comparison, let's do another survey on Beijing's Forbidden City. From 1km we can clearly see the imperial halls and courts. From 12km, the rectangular Forbidden City surrounded by a moat is a distinctly visible feature. Even from 100km, the Forbidden City still appear as a small pod in the middle next to a dark shape of the Beihai lake.

All these are really very logical. The Great Wall is perhaps 5 to 10 meters wide, most of them are now crumbling earth. The Forbidden City on the other hand, have a dimension of about 1000 meters by 800 meters. It is not a surprise that the Forbidden City is far more visible than the Great Wall.

Seeing is believing. The saying that the Great Wall is visible from space is unfortunately only an urban legend.

2007.11.30 [, ] - comments


Jyutping (Cantonese Pronunciation) Table

Initially my blog was focused on technical IT subject. Overtime I have wrote less about that and more on general topics like travel. Today I will return to a technical topic about the Jyutping(粵拼) Cantonese romanization system.

I start off with the quest to learn and master a Chinese input method. Years ago I started with the Cangjie (倉頡) system. I never get much beyond basics because it is a difficult system to learn, let alone to master. Then I looked at pronunciation based system. I am glad to find out Cantonese based system is readily available. Out of the multiple romanization system, people seems to have gravitated toward the Jyutping system by the Linguistic Society of Hong Kong.

So the next step is to get familiar with the Jyutping system, which is not trivial for me because I am weak in phonetics. It will be very useful if there is a service to annotate a piece of Chinese text with the pronunciation under each character. Unfortunately I can find no such software besides some dictionary that does it character by character. Instead I have decided to write one myself, as a naïve translation should not be difficult to write.

Now all I need is a table of all Chinese characters and its Jyutping, i.e. the Jyutping specification. I have spent days searching the internet and come out empty handed. Linguistic Society of Hong Kong themselves provides little more than a general description. It is a shame even some links to its description are broken.

The good news is I have finally found it from the Unicode Han Database, a place I have crossed many time but have not realized they have compiled the most comprehensive data on Chinese characters, including Jyutping and even Cangjie code. With the database here I am ready for business!

(2010-02-17 Thanks Helena for the heads up. The Unihan database format has since changed. The new download link is Unihan.zip. Some general description such as Unicode NamesList File Format are also available. )

2007.11.29 [, , ] - comments


The bilingual Love in the Time of Cholera

A few years ago after returning from a trip to México, I took much interest in Spanish language. I started to study on my own and make some good early progress. As I was quite fascinated by Latin America novelists, I took a bold step to order a copy of Gabriel García Márquez's "Love in the Time of Cholera" in its original Spanish. I only knew basic grammar and limited vocabulary at that time, but I have vowed to learn until I can read the entire novel. Just in case, I have also brought an English copy alongside.

All these years I have never put enough time into learning Spanish. The two books are collecting dust on the bookselves. Just now I have found out "Love in the Time of Cholera" has made into a movie. The movie review is quite bad so I won't bother with it. But it has reminded me I have the novel for a long time, which I have not read beyond the first page. This time I have finally started reading it.

How is it like to read a major novel in a language I only half understand? I have found a rhythm that is quite productive. First of all I do not want to use a dictionary to look up every word I don't understand. This way will be too slow and I cannot truly enjoy the story. Instead I am reading the English edition first, one paragraph at a time. Then I turned to the same paragraph in the Spanish edition and read it again. When necessary I go back to matching sentence in the English and read them side by side. Once in a while I will looking use the dictionary to learn a vocabulary or stop to learn a sentence. Other times there will be sentences simply too difficult for me and I will just resign and move on. I am happy to find I can decode 50% of Spanish this way without other aid. At the same time I can follow the story quite well. I am very attracted to the story of Dr Urbino and Fermina Daza so far. I am going at a pace at least five times slower than if I read the English alone. On the other hand, rather than speed through the story as I usually do, I am savoring every sentence by reading it at least twice.

In truth I mostly rely on the English edition to understand the story. I am reading Spanish with a training wheel. But what a fun trip that is. It is certainly more enjoyable to take a trip on a training wheel than to study in the classroom all the time.

2007.11.25 [] - comments


Cross Cultural Viewpoint

I've posted a comment in response to Tim O'Reilly's blog entry The Other Side of China. It has summarized some of my viewpoint about cross cultural issue. So I think I will repost it here.

Right now the West have two opposing view of China. One is China as an enemy, an oppressive government full of hidden agendas to exploit the world and a threat to welfare that the West enjoyed historically. On the other side are people who are fascinated by the long and glorious history of China and are bullish that the industrious people will propel themselves to the center stage of the world. Obviously both side has elements of truth and neither of them have a complete picture. While I don't hold the negative view, I'd say there is merit on those views. Nor do I think people should idealize China because someday they will be disillusioned when they finally see China's limitation.

Having straddle different cultures myself I have formed some theory regarding these cross-cultural interaction. The opinion people make is often a reflection of themselves. A cynical person focus more on negative issues. An optimists focus more on the positive ones. I think the readers of Radar tend more to be optimists and thus will express more positive opinion than the general public.

An universalist see common value among people despite the outward difference. That's why Tim said "The Chinese are very like us". When one find such insight it can often strike a deep chord. I was so moved by Satyajit Ray's film Aparajito. As an urban kid, my life is as different from previous century's Bengali villagers as it can be. Yet I can totally connect the characters, especially with the scene when the mother reluctantly sent the boy off to city for education. There is a kind of love that is universal and transcend above superficial difference.

A discriminator (a poor term perhaps, I use it without any negative connotation) can sense a small difference between different cultures, like the motorcyclist's remark about "family vs. government". They often express frustrations because of the mismatch in people's thinking and expectation. But being discriminatory is not always a bad thing. Something the contrast leads to better self understanding. For example, this person may now realize in his culture the family plays a bigger role than the government, which is not necessary true in other country. This may never crossed his mind if not for this interaction.

These general ideas aside, I think it is extremely interesting to engage with China today because it is one culture undergoing a massive transformation, from impoverished to prosperity, from rural to urban, from isolated to connected. Not all thing in this transformation will be rosy. Nevertheless many new ideas will emerge and countless stories will need narration. I think this is an very interesting time in history.



Travel Map

I have a lot of fun with this Travel Map application. It allows you to mark on a map all the place you have travelled to. I have diligently checked off every town I have visited whether it is big or small. It ended up with just over 200 places so far! Well the number is really a little be inflated because I have check off dozens of small communities within two hours drive from my home in California. Still it is a fun exercise.

Wai Yip

I did made some serious effort to recall many small towns I have been to. I flipped though some old journals and researched for some places on the Internet. Part of the fun is it helped me to revisit some happy memories in the past.

2007.11.01 [] - comments


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