22nd CIPA Symposium, October 11-15, 2009, Kyoto, Japan

GEOMETRIC CORRECTION OF MEASURED HISTORICAL MAPS WITH A PIXELORIENTED AND GEOBROWSER-FRIENDLY FRAMEWORKAsanobu Kitamoto a,b ,Yoko Nishimura aaNational Institute of Informatics, 2-1-2, Hitotsubashi, Chiyoda-ku, Tokyo, Japan - (kitamoto, yo-nishi)@nii.ac.jpbDept. of Informatics, The Graduate University for Advanced Studies (SOKENDAI)KEY WORDS:

Geometric correction, measured historical maps, line-preserving distance weighting method, evaluation of
accuracy, Geobrowser, Google Earth, Silk Road, Beijing

ABSTRACT:This paper discusses the geometric correction of measured historical maps and the evaluation of accuracy with case studies on Silk
Road maps, “Innermost Asia” and “Serindia,” made by Aurel Stein about 100 years ago, and Beijing maps, “Complete map of
Peking, Qianlong period,” made about 250 years ago. The former case study deals with maps that cover thousand kilometers, and we
delivered the error table for each major oasis in Tarim Basin so that historical maps can be interpreted under information on errors.
The latter case study deals with maps of a city, and we proposed a new geometric correction method “line-preserving distanceweighting method” that focuses on the problem of linear features which are relevant in the map of cities. Based on these experiences,
we summarize this paper with a few points of discussion about how to deal with historical maps, and show the potential of historicalmaps from the viewpoint of spatial visual sources and linkage across multiple databases.
1. INTRODUCTION
This paper discusses the geometric correction of historical maps
which are measured to some extent, but do not have as highaccuracy as today’s standard. We specifically deal with twomaps - (1) the map of Silk Road made by Sir Aurel Stein in the
beginning of the 20th century (about 100 years ago), and (2) the
map of Beijing made under the order of Emperor Qianlong in
the mid of 18th century (about 250 years ago). Those maps are
not pictorial maps in the sense that the spatial structure of thosemaps is relatively accurate. Hence it is clear that those maps
have some errors, mainly due to technological limitation of thetime. Those errors, however, have been unknown and the usageof those maps has been focused on visual interpretation andusage. Making georeferenced maps will open up new vistas forthe usage of those maps.
Therefore, the purpose of this paper is to show the geometriccorrection methods for those two types of maps, andcharacterizes the accuracy of those maps. The paper is divided
into two main parts – the geometric correction of Stein maps,
and that of Beijing maps, because those two types of maps havedifferent characteristics and hence requires different approaches.
Those two maps are also discussed from the viewpoint ofapplications and academic infrastructure. Finally we compare
two approaches and discuss the general issues of historicalmaps. The detail of the Section 2 and Section 3 is described in(Nishimura, 2007) and (Nishimura, 2008).
2. SILKROAD MAPS BY AUREL STEIN
2.1 Description of the maps
Aurel Stein is one of the representative figures in the history of
expeditions in Silk Road in the beginning of the 20th century.
His first expedition was done in 1900, and he explored thecentral Asia four times in his life. The report of the first
expedition (1900-1901) was published as “Ancient Khotan”(two volumes), the second expedition (1906-1908) as“Serindia” (five volumes), and the third expedition (1913-1916)
as “Innermost Asia” (four volumes). In particular, in his second
and third expeditions, Stein surveyed all over Tarim Basin (nowXinjiang Uyghur Autonomous Region of China), which is thecentral part of Silk Road, and he created detailed maps of thearea with longitude and latitude in his reports, Serindia andInnermost Asia. Those maps are still considered as the mostreliable and informative maps of the area, and as the basic
academic references in the study of Silk Road.
The accuracy of maps, however, has not been evaluated for
entire maps, because of the large number of sheets, namely 94
sheets for Serindia and 47 sheets for Innermost Asia. The large
number of sheets makes it difficult to evaluate the accuracy ofthe map across sheets and to understand the entire nature of themap. For the evaluation and usage of the map divided into
many sheets, we need to connect many sheets into one large
map through the georeferencing of sheets and seamlessconnection of them.
2.2 Simple Geometric Correction
Because Stein maps have latitude and longitude on the maps,
we can simply use that information for georeferencing. Namely,using latitude and longitude grid drawn on the maps, we focus
on the intersection of the lines as control points. Because each
sheet has 3 or 4 longitude and latitude lines, we can pick up
about 30 control points for each sheet. Then we focus on aquadrilateral from four neighboring control points, and within aquadrilateral, bilinear interpolation is applied for each pixel.
The interpolation is done from the image coordinate to theworld coordinate and each sheet is georeferenced so that wehave one large georeferenced map connected seamlessly.
During this step, there is a problem of map projection anddatum, because the map projection and datum is unknown (notclearly written) in the Stein’s report. From the inspection ofmaps, we assumed that map projection is a simple geographicallinear projection, so a simple bilinear interpolation works.

About the datum, it is also unknown, but due to the error ofseveral kilometers on the map, which will be described later,
the choice of a datum does not give a significant impact on theevaluation of the map. So we assume that the datum is the sameas that of the current map or satellite images.
After georeferencing, an important next step is to publish themap on the Web so that we can share the maps with many otherpeople. We used the KML standard for publishing the data on
the Web by creating a series of images with different
resolutions, and by organizing them using a so-called “SuperOverlay” method specified in the KML format. Using thismethod, one can reduce the amount of data because images ofappropriate resolutions are retrieved and rendered. The productis now accessible on the Web (http://dsr.nii.ac.jp/geography/).

We selected control points for oases that can be assumed not tomake any movement for these 100 years, and the representative
point of an oasis as the center of the current town.

(a) Serindia(b) Innermost Asia
Figure 2. Distribution of errors on Stein maps using control
points from ruins and oases.
Figure 1. (left) Grid of the original map, (right) Map of
Innermost Asia on Google Earth.
2.3 Control Points for Evaluation
In the previous section, we used the intersection of latitude andlongitude grid as control points for geometric correction.
However, comparison between the corrected map and recent
satellite images on Google Earth shows that their matching is
not accurate. For example, we can focus on a famous ruin
which has not been moved for these 100 years since the Stein’s
expedition. The ruin on the historical maps and on the highresolution satellite image is not mapped onto the same location,or the same latitude and longitude. Obviously the location of
the high resolution satellite image shows the correct location, so
the ruin on the historical maps is located on a wrong place.
Hence we can evaluate the error of the map at control points
selected for evaluation.
Those control points include ruins which can be identified on
Google Earth, and drawn on at least one of Stein maps. Basedon the past survey of the site, and the past experience andmeasurement of one of the authors, we could finally identify 70
control points. It should be remembered, however, that theidentification of ruins on Google Earth is a difficult task
without any experiences of surveys at the site. Hence theidentification of control points is mainly limited to the area
where the author has some knowledge about the site. With thehelp of other experts, however, the number of control points
may be increased in other areas of Silk Road.
Another source of control points is oases. Stein collected many
place names in alphabet, obtained from listening to thepronunciation of local people who speak Uyghur, so thisinformation can be used to identify oases by comparing with thecurrent map of China. Then we identified about 130 control
points from oases. The following caveats should be studied
when using oases as control points.
1.
An oasis might move to a different place due to the
movement of a nearby river, and so on.
2.
An oasis might be extended to suburbs or a new center
might be developed recently, so the representative pointof the oasis can be chosen arbitrary.

2.4 Distribution of Errors
The accuracy of Stein maps is evaluated for about 200 control
points selected as described in the previous section. Figure 2
shows the result. Arrows in the figure starts from the current
location of control points to the location of control points oneach historical map, but the length of arrows is 10 times longer
than the real length for easier interpretation. The result showsthat the overall distribution of errors shows the same tendency.
An error, which is defined as distance between the current
location and the location on a historical map, is roughly
measured to be the order of several kilometers, ranging from
250 meters to 32 kilometers. Observations from the map can besummarized as follows.
1.
Two maps show similar tendencies, indicating that mapsof Serindia and Innermost Asia are related.
2.
Errors are larger in longitude than in latitude.
3.
Direction and size of errors is related to the route of
Stein’s expedition.
4.
Aksu, which is located in the west of Tarim basin, showsa large error to the west.
5.
Ganzhou, which is a city in Hexi corridor, shows a large
error to the east.
6.
Errors in the local neighborhood are relatively uniform, so
errors can be evaluated by major oases in Silk Road.
2.5 Interpretation of Errors
Most of the observations above can be explained from thesurvey method employed by Aurel Stein. He published at least
two references on his maps, of which (Stein, 1923) has adetailed description on the survey. For the most part, they usedplane-table surveys, and more accurate trigonometrical surveys
were used for only a limited part. They also used cyclometers
where plane-table surveys cannot be used. Because the survey
was not the main goal of the expedition, they could not spend
enough time for accurate surveys, so it is natural that the resultof survey has errors for quick processes.
Other fundamental problem is the lack of measurement methods
for longitude. At that time, latitude can be measured accurately
using astronomical survey, but longitude was difficult tomeasure in spite of many researches for accurate measurement.

Wireless communication technology had just begun to be
introduced in that area, so it did not give a significant
improvement on the accuracy of maps. This is the reason thaterrors in longitude are much larger than that in latitude.
Cyclometers are also the reason of large errors, because theerror tends to accumulate as the length of an expedition route
increase without any good points for resetting the error. Thismay be the reason of large errors in some parts of maps.
2.6 Error Table for Major Oases
We assume that error distribution is relatively uniform in thevicinity of a major oasis, but shows different patterns acrossmajor oases. To check the validity, Figure 3 shows an example
of local error distribution around Turfan oasis. The
representative point of this oasis is shown as a star. At this point,
it is measured that the error is about 4.9 kilometers toward
south-west (SW) in Serindia, while the error is about 8.2
kilometers toward west-south-west (WSW) in Innermost Asia.
Other control points have different errors but error distribution
is relatively uniform within this area.
Then we create an error table showing the azimuth and lengthof error for each major oasis. This table can be used as a roughestimate of error for each major oasis. The more detailed
distribution of errors can be obtained using not only control
points but also features on the terrain such as mountain peaks
and valleys that does not change significantly in 100 years. It is
important to use other sources of information such as terrain to
improve the identification of actual positions.
Table 1. Error table for major oases.
Serindia

Innermost Asia

Oasis
Name

AzimuthDistance(km)AzimuthDistance(km)Kāshgar

SW

4.5

NW

1.2

Aksu

W

17.0

W

26.7

Kuchā

W

19.0

W

3.2

Korla

SE

4.3

SW

20.3

Bugur

W

17.9

W

6.5

Khōtan

NE

5.1

N

1.2

Niya

E

2.6

E

3.1

Charklik

ENE

4.4

WNW

10.0

Turfān

SW

4.9

WSW

8.2

Hāmi

SW

6.2

SW

6.2

Mīrān

NE

2.7

NW

12.3

An'xi

E

13.3

E

15.2

Suzhou

E

4.7

E

3.5

Ganzhou

E

32.0

E

15.6

2.7 Gazetteer
Stein also published the list of place names in Innermost Asia,
so this can be used as a gazetteer of Silk Road. Each place has
its name, the sheet number, and the classification of the place.
To use this gazetteer, we digitized this list first, and corrected
several errors, and organize the classification system bymerging similar classes. As a result, we have 5490 place names
into 6 classes (101 detailed classes). This gazetteer is not yet
complete, but is partially accessible from maps so that users cansearch a map sheet from a place name.

Figure 3. Error distribution around Turfan oasis. The starshows the representative point of the oasis. Black arrows:
Serindia; White arrows: Innermost Asia.
3. BEIJING MAP IN QIANLONG PERIOD
3.1 Description of the map“The complete map of Peking, Qianlong Period” was createdaround 1750 under the order of Qianlong Emperor (Reign 17351795) of Qing Dynasty. This is known to be the oldest
measured map of Beijing with the scale of 1/650. This map was
first stored in Forbidden City, discovered in 1935 at National
Palace Museum, and has been stored there since then. The
original map is very large, with the height of 14 meters and thewidth of 13 meters, so the original map is not appropriate forbrowsing and is not accessible to the general public. Available
is the copy of the map, and we use a copy published in 1940 by
Koa’in, and now archived at the Toyo Bunko, the Oriental
Library. This copy is known to be the best copy among others
for the high resolution beautiful printing. Another advantage ofthis copy is the appendix of place names created by the person
who discovered the map later.
The problem of this map is also the large number of sheets. The
map is divided into 17 lines from north to south, and 11-13
pages from east to west, and the total number of sheets amounts
to 203. With this number of sheets, it is difficult to study theconnectivity of neighboring sheets, and the characterization of
the entire map has not been feasible. For the evaluation andusage of the map divided into many sheets, we need to connect
many sheets into one large map through the georeferencing ofsheets and seamless connection of them.
3.2 Geometric Correction for Beijing Map
A large difference between this map and Stein maps addressedin the previous section lies in the presence of latitude andlongitude on the map. Stein maps had latitude and longitude,even if they are not correct. For the Beijing map, however, it
does not have that information, so control points should beselected from the historical map and the current satellite image
for geometric correction.
A typical method of geometric correction using control points isbased on Delaunay Triangulation (Triangular Irregular
Network). This method organizes control points into a networkof triangles, and estimates local geometric correction
parameters for each triangle. This method is established and has
been applied to many maps, but this method has an important
problem in our case. The first problem is a minor problem; if
the distribution of control points is skewed, the Delaunay
Triangulation produces skewed triangles, which lead to a
deteriorated result for those triangles. The second problem,
which is a more fundamental problem, is about the preservationof linear features in a city, such as streets and surrounding walls.
Geometric correction by Delaunay triangulation transforms astraight line to a poly-line, which may look like a zig-zag line.

In Beijing, straight lines are symbolic features of the city, so thepreservation of linear features is an especially important
requirement in the geometric correction. Hence a traditional
method cannot be used for this task.
To solve this problem, we propose a new geometric correction
method, namely “line-preserving distance weighting method.”This method is an extension to a traditional distance weighting
method so that it can preserve linear features, such as streets
and walls. In the following, we will introduce the basic idea of
our method in addition to traditional methods.

z l ( x ) = ∑k wk [(1 − t ) z i + tz j ] / ∑k wk
We use the same function for wk . Finally we obtain the valuez ( x) at point x as the linear combination of values fromcontrol points and control lines.

z ( x) = w p z p ( x) + (1 − w p ) zl ( x)Here the parameter0 < w p < 1 represents the relative

importance of control points, and we set w p = 0.25 .

Figure 4. Concept of distance weighting methods
3.3 Line-Preserving Distance Weighting Method
3.3.1 Distance weighting method for control points
The basic idea of distance weighting methods is that the effectof control points is modelled as the function of distance
between a control point and the point to interpolate. As in
Figure 4 (a), suppose that we interpolate point x usingN

control

pointsintheneighborhood,namely xi (i = 1,K N ) , where the point xi takes value zi .
In this paper, zi represents a vector of displacement from thehistorical map to the current map. Then the value z p ( x ) at
point x is computed as the weighted sum.

3.3.3 Query on Control Points and Control Lines
The disadvantage of our method is the computation cost. Our
method is pixel-oriented in the sense that geometric correction
parameters should be estimated for each pixel. This is incontrast to Delaunay triangulation-based methods whereparameters need to be estimated for the unit of a triangle.
Estimating parameters for each pixel requires much higher
computation cost, but leads to smooth interpolation results. To
reduce the computation cost of this method, we need a spatial
access method to speed-up searching nearest control points andlines from the database. The most basic method is linear scan ofpoints and lines, but the indexing of control points and lines
should be considered. We currently use kd-tree for control
points, and for control lines, we sample a line by a set of points
and index those points in a kd-tree as special points of the line.
However, we need to evaluate other indexing methods, such as
quadtree to find out the best indexing method for this problem.

z p ( x) = ∑i wi zi / ∑i wi
The weights wi are the function of distance d i between thepoint

x and a control point xi . We use a function2
wi = (1 − d i2 / d max) where d max is distance to the Nthnearest control points. We set N = 5 .

3.3.2 Distance weighting method for control lines
We extend this method naturally to control lines for preserving
linear features relevant in the map of cities. Mathematicallyspeaking, a line is a set of points. Hence we can regard a control
line as a set of points whose values change continuously fromone endpoint to another. Then we can define a virtual control
point on a control line whose distance can be measured on theperpendicular line to the control line. Namely, distanced k between point x and control line lk is defined as length ofthe perpendicular line to p k , which is the virtual control pointon the control line. Assuming the endpoints of control line lk
are

xi and x j , and define a parameter t on the line

as t =| p k − x i | / | x j − x i | . Then value z l ( x ) at point

x is the linear combination of M lines lk (k = 1, K M ) ,Figure 5. (left) Control points selected on Google Earth. Cyanand red represents the current and the old location, respectively.
(right) Distribution of control points and control lines.
3.4 Control Points and Lines
We selected about 1800 control points from palace, large
houses, intersections of streets and hutongs. These are regarded
as features that have not been moved for these 250 years. In
addition, we selected about 500 control lines from streets andsurrounding walls of the inner and outer castle. Those points
and lines are identified on the current satellite image of Google
Earth, and later used for geometric correction. We createdsoftware for geometric correction, and applied it to the problemof 29 billion pixels on 203 sheets. For this large scale problem,
we used Linux clusters to speed up the process. The final
product is available at “Digital Maps of Old Beijing”(http://dsr.nii.ac.jp/beijing-maps/).

3.5 Discovery of Mis-arrangement
Control points and lines are used in our proposed geometriccorrection method, and we obtained seamlessly connected mapthat can be viewed on Geobrowsers. However, the study of theresult revealed that some parts of the map seem to be inaccurate,
so we studied the reason of this problem.
The problem was found in the west of the outer castle, and we
observed the following problems.
1.
Some parts are too different from the current map.
2.
Some regional features (such as temples) are notconnected across neighboring sheets.
3.
Some features that should be located at the current place
are found in wrong places.
These problems cannot be explained simply by the inaccuracyof the map. Hence we hypothesized that map sheets arearranged in a wrong manner. Then we discovered that thehorizontal exchange of sheets between neighboring sheets andexchange of half-sheets within a sheet can solve allinconsistencies present on the map. Mis-arrangement occurredon 5 sheets as Figure 6 shows.

occurs during the editing process of the copy, where only intrapage mis-arrangement could occur. These observations suggestthat the mis-arrangement of the historical map was caused by
the restoration after the map was found later.
3.7 Gazetteer
As addressed before, the copy of the map has the list of place
names, and it is known to be the most reliable index available
because it is made soon after the discovery of the map. So wedigitize this list, and checked the correctness of place names bycomparing each place name with the map. As a result, we foundout that of around 3600 place names, about 800 place names
contain errors. We also found out that about 400 place names
are missing from the index. We corrected those errors and now
the gazetteer has about 4000 place names. To allow
multilingual access, we added Japanese, simplified Chinese,and Pinyin in addition to traditional Chinese, which is theoriginal language of the index. Furthermore, some place names
are georeferenced so that access to place names from Google
Earth is possible. As a result, we created a gazetteer of Beijing
which is more comprehensive and reliable than the original.

3.6 Interpretation of Errors
It has been known that the map has some errors. (Hou, 1988)
reported that some parts of the Qianlong map have errors indirection and scale. (Ihara, 1997) also reported that thehistorical map cannot be matched with the neighborhood of
Fayuan si, and research should be based on not only this map
but also on other maps currently available. Finally (Li, 2004)
reported that he has found the mis-arrangement (exchange ofsheets for the horizontal direction) at 9, 10, and 11 pages ofLine 14. Those results, however, just pointed out some errors
they found, but the study of the entire map has not been done
due to the large number of sheets. Hence the accuracy of themap has been unknown, but our analysis on georeferenced map
revealed that the map is relatively accurate.
1.
Mis-arrangement can be found not only on Line 14, butalso on Line 15 and Line 16. The number of pages
involved in mis-arrangement is five. However, there is no
problem in Page 9 of Line 14 as Li pointed out.
2.
The problem around Fayuan si is due to the misarrangement in that part, and not due to the inaccuracy ofthe map. After rearrangement, the historical map can becompared with the current map.
Finally, we found two clues on the cause of mis-arrangement.
Firstly, the mis-arrangement is found on fragmented parts
which were later restored (there is no record on this restoration,
however). Secondly, the mis-arrangement within a sheet never

4. DISCUSSION
4.1 Advantages of Geobrowsers for Historical Maps
Geobrowsers such as Google Earth was used for the important
steps of this research, namely the selection and management ofcontrol points (and lines), and the publication of maps on theInternet. Another important part, namely geometric correction,
was done by software made by ourselves. We suggest thattraditional GIS software, which has been used by many
researchers for historical maps, has several limitations incomparison to Geobrowsers. Firstly, it does not have highresolution satellite images as default base maps for free. They
can be purchased for the city level, but it is not feasible over theentire Tarim Basin (in addition, high resolution maps of Tarim
Basin are not available due to military reasons of Chinese
government). This suggests that the geometric correction of
Stein maps, in particular, was not realistic before theintroduction of Geobrowsers. Secondly, Geobrowsers aredesigned for the Internet environment, so the publication of data
in a Geobrowser-friendly format such as KML is not difficult.
Even an extremely large map can be published on the Internet
so that people can see any part of the map using zooming-in andzooming-out functions. On the contrary, the publication of datausing traditional GIS is not easy, and usually involves thedevelopment of a dedicated system. Thirdly, Geobrowsers are

Figure 6. Mis-arrangement in the west of the outer castle. (left) before correction; (right) after correction.

designed for novice users and the functionality is limited, so
learning cost for novice users is lower as a result. Annotationand management of control points and lines is alsostraightforward and does not require the training of software.
Those advantages are the reasons that we used Geobrowsers asa main platform for historical maps.
The current disadvantage of this framework, however, is that
there is no integrated platform for this workflow. Import andexport of data requires the handling of data on the role ofadministrators. To solve this problem, we need integrated
software for this workflow so that even novice users canmanage the workflow by themselves.
4.2 Complexity of Geometric Correction
Geometric correction of historical maps is an indispensable stepfor providing digital maps in a usable manner, and we showed
two approaches in this paper. The first approach is to apply asimple geometric correction method, and show an error table atcontrol points. The second approach is to apply a complex
geometric correction method so that the historical map can bedirectly compared with the current map. Note that the first
approach can be considered as producing an intermediate
product before the second approach, because control points forevaluation can be used for geometric correction in a later stage.
However, the second approach is not always the best solution.
When we do not have enough control points, even if geometriccorrection is accurate at control points, the map may be
deformed so significantly that its appearance is too much
distorted. Some users may not accept this result.
In a wider context, this problem may be considered as aproblem of overfitting, which refers to a good balance between
the goodness-of- fit and the number of parameters. If weincrease the number of parameters, we can improve thegoodness-of-fit, but the usage of too many parameters results incomplex interpolation, and fitting becomes worse at points
which are not evaluated. Hence a good balance between fitness
and parameters needs to be found for interpolation problems.
We have not considered this problem in this context, but wefeel that the goodness-of-fit is not the only factor to evaluate theusability of the historical map.
4.3 Spatial Visual Resources
In addition to historical maps, we also have other resources withspatial coordinates such as historical photographs. To deal withthese resources, we propose a concept of “spatial visual
resources,” which is the union of spatial resources and visual
resources. Here spatial resources have spatial coordinates which
can be georeferenced, and visual resources have visual
information which can be interpreted. The union of those two
resources allow us to better understand the real scene.
For example, we identified one ruin from Stein maps where thepresent location has been unknown. We combined the historical
map and several historical photographs, and identified thepresent location through the visual comparison of historicalphotographs with the real landscape. Another interesting result
from Beijing map is about the real scene of streets. A widestreet on the map is actually a narrow street on the photographs
because houses and shops invaded into the street. This fact has
been described in text, namely books and records, but the realscene can be understood only from spatial visual resources.

4.4 Linkage across Multiple Databases
Because of the limitation of the space, we did not deal with theapplication of the maps. However, from the analysis of Steinmaps, an interesting application is emerging, namely what wecall “digital excavation.” This concept refers to our method of
digging the “cyberspace” to find out important clues for ruins.
In that context, we are interested in making links between
multiple databases, especially the reports made by European
expeditions in the early 20th century and the databases made by
local cultural heritage offices in China. To make links across
many records in the database, the key technology is nameidentification and place identification.
The identity of names is the easiest case to make a link, but
usually the same ruin is registered in different names withvariation, so we need to make rules to match between
differently represented names. Another interesting clue is place
identification, where the similarity of spatial coordinates is used
for making links between database records. For thisidentification to work, we need to apply geometric correction tohistorical maps, and georeference the feature to the correct
location. Using this approach, we have already identified a few
ruins which were recorded by European expeditions but later
rediscovered as new ruins by Chinese cultural heritage offices.
Making links between European expedition records and local
surveys is a promising direction for digital excavation.
5. CONCLUSION
We discussed the geometric correction of historical maps withtwo case studies. Both historical maps have not been evaluated
due to the large number of sheets, but we applied our geometriccorrection method to provide them as seamless maps accessibleon the Internet. They also have potential in new research areas
such as digital excavation. Future work includes making ageobrowser-friendly framework so that people can easily use
the workflow described in this paper.
References
Hou, 1988. 北京歴史地図集, 北京出版社, pp. 41-42.
Ihara, H., 1997. 加摹乾隆京城全図再論; 法源寺界隈を手がかりに, 吉田寅先生古希記念アジア史論集, pp. 323-339.
Li, 2004. 美国国会図書館所蔵中文古地図叙録, 文物出版社,
pp. 105-106.
Nishimura, Y. et.al., 2007. Analysis of Silk Road Old Maps
Using Google Earth. Information Processing Society of Japan,
SIG Computers and the Humanities Symposium 2007, pp. 155162.
Nishimura, Y. et.al. 2008. Information Infrastructure of Beijing
Historical Space Using Google Earth and Complete Map of
Peking, Qianlong Period", Information Processing Society ofJapan, SIG Computers and the Humanities Symposium 2008,
pp. 81-88.
Stein, A., 1923. Memoir on Maps of Chinese Turkestan andKansu: From the Survey made during Sir Aurel Stein’s
Explorations.
1900-1,
1906-8,
1913-15.
DehraDūn,
Trigonometrical Survey office.