the land area of the earth is covered by principal arcs 
of triangulation and by Shoran and Hiran nets. The 
gaps between the triangulation arcs or the Shoran 
and Hiran stations measure approximately between 
100 and 1500 kilometers. In many countries, these 
gaps are filled in with geodetic triangulation of lower 
order and by levelling. It will take however many 
more years to cover the land area of the earth with 
a sufficiently dense network of homogeneously distri- 
buted horizontal and vertical control. The situation 
becomes even more problematic when this require- 
ment is extended over the water areas of our planet. 
In many countries, a first order control network is 
all what can be requested for small scale mapping in 
scales 1/500 000 and smaller, although such maps 
are of a rather limited value for technical and econo- 
mic development. 
Medium scale maps at scales like 1/250 000 to 
1/50 000 very often must be considered as adequate 
for certain development purposes. The compilation of 
these maps requires a much denser network of con- 
trol when compared with small scale mapping. An 
inventory of the existing networks shows that much 
less than half of the land area of the earth is covered 
by networks sufficiently dense to permit the compi- 
lation of medium scale maps. 
For the economic and technical development of 
many countries, maps at the scale 1/25 000 or larger 
are an essential requirement. To compile maps at 
this scale, one control point per square kilometer is 
desirable. Such a density of geodetic control exists 
for only about one percent of the land area of the 
world. 
As a result of this brief analysis, one can con- 
clude that in the future the extension of geodetic con- 
trol networks must progress at such a rate that the 
cartographic compilation at different scales and sub- 
sequently the technical and economic development of 
most countries will not be handicapped. A more in- 
tensified use of the latest methods for the extension 
of geodetic control like electronic distance measure- 
ment and aerial triangulation appears to be at least 
partially an answer to this problem. 
With reference to the cartographic compilation 
on a world-wide level, the greatest progress has been 
made in small scale mapping, such as for instance 
The International World Map at the scale 1/1 000000. 
This project is coordinated by the United Nations 
(Cartographic Section) and is almost completed. 
Maps at this particular scale are already available 
and cover about 85 % of the land area of the earth. 
The percentage of mapping at larger scales ac- 
tually completed all over the world (in recent years 
nearly entirely by photogrammetric procedures) is 
approximately as follows at the respective scales: 
1/250 000 or larger 35 %, 
1/100 000 sale range 15 % to 20 %, 
1/25 000 or larger not more than 5 %, 
including cadastral plans. 
For the exploration of natural resources, topo- 
graphic maps at scales larger than 1/100 000 are 
particularly valuable. According to the preceeding 
inventory, mapping completed at this scale covers 
only about 15 % of the land area of the world. 
Assuming that this cartographic coverage could 
be completed within approximately 50 years, the an- 
nual progress would be equal to only 0.3 % of the 
land area of the earth, or approximately 400 000 sq. 
kilometers per year assuming a linear increase. 
Taking this value as an argument in terms of annual 
progress, it can easily be deduced that another 300 
years would be needed to complete the mapping of 
the continental earth at scales larger than 1/100 000. 
It is obvious that a period of 300 years is ex- 
cessive and cannot be justified economically. Effici- 
ency has fortunately improved during the last years 
due to the development of more efficient methods and 
the rate of annual progress has increased proportion- 
ally. It is also necessary to take into consideration 
that large areas of the world are considered as having 
a very limited economic potential. Nevertheless, it 
must be concluded that at the actual rate of yearly 
progress, the completion of an adequate map coverage 
of the continental earth at scales larger than 1/100 000 
would take another 100 to 150 years. Consideration 
of the correlation between topographic cartography 
and the solution of problems like world-wide under- 
nutrition and the so called "population explosion", 
lead to the conclusions that the cartographic progress 
is still too slow and that there is an absolute necessity 
to double or triple the efforts in this field; otherwise, 
it is very likely that the technical and economic deve- 
lopment of many countries will be hampered by a too 
slow advance in cartographic operations. 
An inventory of map coverage on a national as 
well as on an international level must necessarily in- 
clude an evaluation of the present status of map re- 
vision. Such an analysis does not produce a very 
bright picture. There are relatively few countries in 
which map revision is up to date. In a much larger 
portion of the world, the existing maps are of reduced 
value because they were or they are not periodically 
revised. It is doubtless that in this field i.e. in map 
revision, much greater efforts must be made in the 
future, particularly in urban areas. At the present 
time, the rapid changes of planimetry and even of 
topography in these areas already present a serious 
problem as far as map revision is concerned. Many 
maps are already obsolete at the very day of their 
publication. We face here the problem and the chal- 
lenge of fast changing input material which must be 
compatible with specific output requirements, i. e. 
with standard map specifications. As a consequence, 
the future will force us to abandon to a certain extent 
the static conception of planimetric and topographic 
features of the past in map making and to ^dopt a 
dynamic conception when dealing with map compi- 
lation. The old conception of an essentially time-in- 
variant planimetry and topography in two or three 
dimensions is becoming obsolete; and in the future, 
the fourth dimension, namely time, i. e. the continue- 
ously faster changing planimetric and topographic 
features will have an increasing influence on map 
compilation. 
As already mentioned, the world's population 
will be doubled in the year 2000 and the urban areas 
might eventually amount to more than 15 96. of the 
world's entire land area. With adequate efforts we