1. Mapping History
(starting with Manchester)
Frankie Roberto
frankie@frankieroberto.com
Twitter: frankieroberto

2. Currently, OpenStreetMap
maps change over time, as
people edit them.

3. ...in a way that printed maps don’t.
N.B. This map, in Sheffield, has been like this for months.

4. But these changes represent
the speed at which editors
update and improve the
maps, not the speed of
changes on the ground.

5. I’d like to be able to add a
time-slider to maps, so that
you can see how the places
themselves have changed
over time.

6. Comparing old maps with
new maps is fun...

7. Before...

8. After...

9. But these comparisons are
made harder by the big
changes in cartography.

10. I’ve mapped some of the buildings in Manchester...

11. ...where there are lots of pretty old buildings...

14. ...and some ugly newer ones...

15. ...as well as a few under construction.

16. (I’ve shared all the photos on Flickr)

17. ...where they are even machine tagged with the appropriate way.

19. The years in which the
buildings were constructed
have been added to
OpenStreetMap using...

20. start_date=

21. This information can
sometimes be found
inscribed on the buildings,
but for the most part I used
the local library...

22. Isn’t it pretty?

23. Books like this were a great help.

24. ...it even has a gazeteer, listing the buildings by street.

25. So, given this data, how do
you filter out new buildings
from old maps?

26. You could add extra rules
to Mapnik or Osmarender.
...but it’s probably easiest
to pre-process.

27. <?xml version="1.0" encoding="ISO-8859-1"?>
<xsl:stylesheet version="1.0"
xmlns:xsl="http://www.w3.org/1999/XSL/Transform">
<xsl:template match="@*|node()">
<xsl:copy><xsl:apply-templates select="@*|node()"/></xsl:copy>
</xsl:template>
<xsl:template match="way">
<xsl:choose>
<xsl:when test="tag/@k = 'start_date'">
<xsl:choose>
<xsl:when test="tag[@k = 'start_date']/@v &gt; $year">
</xsl:when>
<xsl:otherwise>
<way><xsl:apply-templates select="@*|node()"/></way>
</xsl:otherwise>
</xsl:choose>
</xsl:when>
<xsl:otherwise>
<way><xsl:apply-templates select="@*|node()"/></way>
</xsl:otherwise>
</xsl:choose>
</xsl:template>
...using a little bit of XSLT.
</xsl:stylesheet>

28. #!/bin/bash
for (( i = 1900; i < 2011; i = i + 10))
do
xsltproc --stringparam "year" "$i" start_date_filter.xsl data.svg > data/$i.osm
done
A quick bash script produces one filtered data file per decade:
1800.osm 1910.osm
1810.osm 1920.osm
1820.osm 1930.osm
1830.osm 1940.osm
1840.osm 1950.osm
1850.osm 1960.osm
1860.osm 1970.osm
1870.osm 1980.osm
1880.osm 1990.osm
1890.osm 2000.osm
1900.osm 2010.osm

29. #!/bin/bash
for (( i = 1900; i < 2011; i = i + 10))
do
ln -s ../files/$i.osm data.osm
xsltproc osmarender.xsl osm-map-features-z17.xml > svg/$i.svg
done
...and then another bash script renders each file using Osmarender:
1800.svg 1910.svg
1810.svg 1920.svg
1820.svg 1930.svg
1830.svg 1940.svg
1840.svg 1950.svg
1850.svg 1960.svg
1860.svg 1970.svg
1870.svg 1980.svg
1880.svg 1990.svg
1890.svg 2000.svg
1900.svg 2010.svg

30. A quick caveat...

31. A quick caveat...
start_date_filter.xsl expects start_date=YYYY

32. A quick caveat...
start_date_filter.xsl expects start_date=YYYY
but the actual date might be:

33. A quick caveat...
start_date_filter.xsl expects start_date=YYYY
but the actual date might be:
1934-10

34. A quick caveat...
start_date_filter.xsl expects start_date=YYYY
but the actual date might be:
1934-10
1934-10-23

35. A quick caveat...
start_date_filter.xsl expects start_date=YYYY
but the actual date might be:
1934-10 c1830
1934-10-23

36. A quick caveat...
start_date_filter.xsl expects start_date=YYYY
but the actual date might be:
1934-10 c1830
1934-10-23 1900s

37. A quick caveat...
start_date_filter.xsl expects start_date=YYYY
but the actual date might be:
1934-10 c1830 1832-1847
1934-10-23 1900s

38. A quick caveat...
start_date_filter.xsl expects start_date=YYYY
but the actual date might be:
1934-10 c1830 1832-1847
1934-10-23 1900s “before 1832”

39. A quick caveat...
start_date_filter.xsl expects start_date=YYYY
but the actual date might be:
1934-10 c1830 1832-1847
1934-10-23 1900s “before 1832”
Figuring this out is a TODO...

40. Here’s how the rendered files look:
1 80 0

41. 18 1 0

42. 1820

43. 1830

44. 1840

45. Theatre Royale
1850

46. Free Trade Hall
1860

47. Lloyd’s House
1870

48. Town Hall
Train station
1 880

49. Elliot House
1 89 0

50. Train station goods warehouse
1900

51. Midland Hotel
19 1 0

52. St George’s House
1920

53. 1930

54. Town Hall Extension
Central Library
1940

55. 1950

56. Peter House
1960

57. Lincoln Square
1970

58. 1 980

59. Heron House
1990

60. 20 0 0

61. Great Northern Tower
20 1 0 (?)

62. But there’s a problem with this map!
There are buildings I don’t have dates for yet
But more importantly, there are old buildings,
long demolished which should be shown.
1 80 0

63. Take a look at this old map of the area for example...
We could trace all these old buildings, and tag them with...

64. end_date=

65. But there’s a problem:

66. But there’s a problem:
We don’t want long-demolished
buildings appearing on the maps!

67. But there’s a problem:
We don’t want long-demolished
buildings appearing on the maps!
Renderers could filter out features with
end_date < Date.now...

68. But it’d probably be best to
move the filtering to the API:

69. But it’d probably be best to
move the filtering to the API:
GET http://www.openstreetmap.org/api/0.7/[...]?date=1932

70. But it’d probably be best to
move the filtering to the API:
GET http://www.openstreetmap.org/api/0.7/[...]?date=1932
Default = [today]

71. We also need to date attributes:

72. We also need to date attributes:
• Name changes (old_name=)

73. We also need to date attributes:
• Name changes (old_name=)
• Change in use (amenity=cinema becomes sport=bingo)

74. We also need to date attributes:
• Name changes (old_name=)
• Change in use (amenity=cinema becomes sport=bingo)
• Change in scale (highway=unclassified to highway=primary)

75. We also need to date attributes:
• Name changes (old_name=)
• Change in use (amenity=cinema becomes sport=bingo)
• Change in scale (highway=unclassified to highway=primary)
• Accessibility modifications (bicycle=yes)

76. One solution is add two extra columns:

77. One solution is add two extra columns:
Tag start_date end_date
amenity=bank 1934 2001
name=Lloyd’s Bank 1934 2001
landuse=construction_site 2001 2002
amenity=pub 2002
name=Wetherspoons 2002
wheelchair=yes 2005

78. One solution is add two extra columns:
Tag start_date end_date
amenity=bank 1934 2001
name=Lloyd’s Bank 1934 2001
landuse=construction_site 2001 2002
amenity=pub 2002
name=Wetherspoons 2002
wheelchair=yes 2005

79. One solution is add two extra columns:
Tag start_date end_date
amenity=bank 1934 2001
name=Lloyd’s Bank 1934 2001
landuse=construction_site 2001 2002
amenity=pub 2002
name=Wetherspoons 2002
wheelchair=yes 2005

80. One solution is add two extra columns:
Tag start_date end_date
amenity=bank 1934 2001
name=Lloyd’s Bank 1934 2001
landuse=construction_site 2001 2002
amenity=pub 2002
name=Wetherspoons 2002
wheelchair=yes 2005

81. One solution is add two extra columns:
Tag start_date end_date
amenity=bank 1934 2001
name=Lloyd’s Bank 1934 2001
landuse=construction_site 2001 2002
amenity=pub 2002
name=Wetherspoons 2002
wheelchair=yes 2005

82. One solution is add two extra columns:
Tag start_date end_date
amenity=bank 1934 2001
name=Lloyd’s Bank 1934 2001
landuse=construction_site 2001 2002
amenity=pub 2002
name=Wetherspoons 2002
wheelchair=yes 2005

83. One solution is add two extra columns:
Tag start_date end_date
amenity=bank 1934 2001
name=Lloyd’s Bank 1934 2001
landuse=construction_site 2001 2002
amenity=pub 2002
name=Wetherspoons 2002
wheelchair=yes 2005

84. We may also need to date
changes in positions (nodes)

85. We may also need to date
changes in positions (nodes)
• Boundary changes

86. We may also need to date
changes in positions (nodes)
• Boundary changes
• Extensions to buildings

87. We may also need to date
changes in positions (nodes)
• Boundary changes
• Extensions to buildings
• Road straightening

88. We may also need to date
changes in positions (nodes)
• Boundary changes
• Extensions to buildings
• Road straightening
• Flooding?

89. The solution is probably to use
Relations (??)

90. Dating things poses some
Philosophical Issues

91. How long does a feature remain the same feature?
(Is a building with a preserved facade the
same building, or a new one?)

92. Final thought....

93. Final thought....
Can we predict the future?

94. Final thought....
Can we predict the future?
(Should we tag planned new
buildings, roads and features?)

95. Thanks
(get mapping history!)
Frankie Roberto
frankie@frankieroberto.com
Twitter: frankieroberto