70 
imagery, with a pixel size of 30 metres and 
a base-to-height ratio of 0.1, is limited to 
an elevation accuracy of at best 60 metres 
RMS. SPOT stereo imagery, with a pixel size 
of 10 metres and a base-to-height ratio of 
0.5-1.0, should produce an elevation 
accuracy of about 10 metres RMS (Cooper, 
Friedmann, and Wood, 1985). This is 
suitable for 1:50,000 scale mapping (and 
larger scales for many applications). 
The SPOT PLA imagery should meet typical 
1:50,000 scale map content standards, except 
in the detailed interpretation of some 
cultural features, where aerial photographs 
are also limited. Natural planimetric 
features can be interpreted accurately 
enough for 1:50,000 scale maps from 
LANDSAT-TM or SPOT. 
COSTS 
The costs involved in the production of 
topographic base maps vary greatly, 
depending on the type of terrain being 
mapped, and the type of mapping being done. 
However, typical figures can be used for 
compa rison. 
The costs for digital mapping methods are 
usually broken down as follows: ground 
control, aerial photography, photogrammetric 
feature and terrain extraction, editing, 
verification, and plotting. 
In Canada, the cost of obtaining ground 
control ranges from $400 to $8,000 per 
control point depending on terrain and 
location. Using a minimum of five control 
points per map, control could cost $2,000 to 
$40,000 per map. Using the satellite 
mapping technique, the required control 
drops from five per map to seven points per 
sixteen maps, or about one control point for 
every two maps ($200 to $4,000 per map). 
The cost of obtaining ground control is 
one-tenth of that required for 
photogrammetric purposes. 
The cost of obtaining image data for 
elevation and planimetric extraction is 
considerably less than obtaining aerial 
photographs. LANDSAT-TM imagery costs about 
$0.09 per square kilometre. SPOT imagery 
should cost about $0.60 (projected U.S. 
price) per square kilometre. This compares 
to a cost of about $1.50 per square 
kilometre for new high-altitude aerial 
photography. 
The current cost of terrain and planimetric 
extraction for 1:50,000 scale maps, produced 
in Canada, is approximately $25,000. This 
is divided evenly between planimetry and 
topography. Through the use of the 
automated elevation and planimeteric 
extraction techniques discussed in this 
paper, it should be possible to perform the 
same function on the computer for under 
$7,000. 
Total costs of the satellite image-derived 
map should be about $10,000 per map (This 
includes all steps from control and image 
acquisition through to map plotting). This 
compares to current costs averaging $50,000 
per map using photogrammetric methods. 
SUMMARY 
Satellite imagery can be corrected to a 
planimetric accuracy suitable for 1:50,000 
scale mapping. When corrected with accurate 
control points and removal of terrain relief 
error, both LANDSAT TM and SPOT imagery can 
meet NATO class "A" standards for 1:50,000 
mapping planimetry. LANDSAT stereo imagery 
does not provide sufficient resolution or 
base-to-height ratio to meet elevation 
accuracy standards for 1:50,000 mapping. 
However, SPOT stereo imagery with increased 
pixel resolution and a larger base-to-height 
ratio should produce elevation accuracy of 
about 10 metres RMS. This translates to a 
20 metre contour interval for 1:50,000 scale 
mapping. 
The sample map shows the feasibility of 
producing base maps from satellite imagery. 
By integrating all of the components used to 
produce the map into a single, tightly 
linked system it will be possible to produce 
such map products operationally in a very 
high throughput environment. 
A map with content based solely on satellite 
imagery can be produced in less than 24 
hours, compared to weeks by photogrammetric 
methods. Automatic processing steps would 
be performed by the computer unattended 
overnight, leaving the machine free for 
interactive work during the day. (This 
assumes that imagery and control data is 
available already and neglects physical 
plotting time). It includes input, 
correction, and geocoding of the imagery, 
and extraction of elevation, planimetric, 
and thematic data. 
The cost of such techniques would be about 
$10,000 per mapsheet including field 
acquisition of new ground control suitable 
for correcting satellite imagery (these are 
current best estimates). Comparable costs 
for photogrammetric mapping average at 
$50,000 per mapsheet. These figures are 
based on steady state production as part of 
a long-term program, and include capital 
equipment depreciation and labour as well as 
data costs. 
The potential for mapping from satellite 
imagery appears to be great. Using existing 
technology, a sample map has been created 
and demonstrated in this paper which shows 
the potential feasibility of such mapping 
systems. In the near future, fully 
integrated mapping systems will be developed 
which will produce cartographically accurate 
maps from raw satellite imagery. Such 
systems will be both economical and fast 
when compared to conventional techniques and 
will provide new products to the mapping 
community due to the digital nature of the 
source data (see Figure 3). 
FIGURE 3 - 3-D View of Adam River 
(LANDSAT Imagery and Derived DTM) 
Cooper, 
S .A. , 
Digital 
Images 
36th 
Congress 
Friedman 
Magnusse 
S., "Mul 
Spacebor 
Control 
Engineer 
49, No. 
1983 . 
Gue rtin, 
Potentia 
Products 
Canadian 
Winnipeg 
Welch, R 
"Compara 
Accuracy 
Landsat- 
Image Da 
and Rem 
pp. 124 
Welch, R 
SPOT 
Engineer 
51, No . 
Yee, B. 
Sondheim 
for Smoo 
accepted 
INTERFAC 
1986 .