print to print, and especially from flightline to 
flightline than has been common practice. We 
have found that prints from a normal black- 
and-white negative are more interpretable 
when processed on contrast 3 paper if the sub- 
jects of interest are shrub steppe, grassland, 
forest openings, or savanna vegetations. 
As a standard practice, we always provide a 
sample print of satisfactory tone values and 
contrast with all orders for photographic 
prints, with instructions to match the quality 
of the sample. All of these guidelines and ideas 
need further research and refinement; how- 
ever, until this can be achieved, these sugges- 
tions will help one obtain more consistently in- 
terpretable black-and-white photography. 
Photo Interpretation Aids 
When taxonomic units are determined, de- 
scriptive legends written, and image-subject re- 
lations worked out, various photo interpreta- 
tion aids are required for the full use of aerial 
photography as a working tool in range re- 
source analysis and management. We have ex- 
perimented with three types of photo interpre- 
tation aids. All three types have their place in 
an operational program. They are the kind of 
items that people must develop for their own 
areas because the aids must be individualized 
to the scale, kind, and quality of photography 
in use on each project. Once the main image- 
subject relations have been determined for a 
project area, one should develop these aids to 
facilitate as many reliable interpretations as 
possible, and hold additional ground examina- 
tion to a minimum consistent with the accu- 
racy requirements and objectives of each proj- 
ect. Two of the kinds of guides we have de- 
veloped are particularly useful as training 
aids. The third is a reference set of identified 
stereograms for use in regular project inter- 
pretation. 
The first training aid consists of a series of 
full, three-photo stereo models in which unique 
images are circled, identified by ground exami- 
nation, described, and the subject photo- 
graphed on the ground. This material is then 
organized in a folder for study and reference 
by the trainee as he relates the ground record 
to the photo images and studies their charac- 
teristics. The central member of such a stereo 
set is illustrated in figure 4. These sets are cho- 
sen by examination and stratification of a 
flight index mosaic and by selection of one or 
two stereo models from within each stratum. 
Stratification is based on similarities of land- 
form, gross vegetation similarities as judged 
from the small-scale images, and the general 
patterns of tone seen on the index mosaic. 
These training sets can also be used as a refer- 
ence during interpretation if one selects the 
models from the project area and works out- 
ward from each model in the course of pretyp- 
ing and operational interpretation. 
The second type of training aid consists of 
some carefully selected stereo models assem- 
bled in a 2 by 2 or 214 by 214 format for 
pocket stereoscope or eyeball stereo viewing 
(fig. 5). Each model is selected to represent an 
important subject, but each also includes 
associated images. The main image in each 
stereogram is named and thoroughly described. 
Its identifying characteristics are indicated, 
and its interpretation is discussed with respect 
to the following topics: Normal variations, 
normally adjacent features for which it may be 
mistaken, associated and convergent evidence, 
and estimated reliabiltiy of photo interpreta- 
tion. 
The third type of training aid is a working 
set of stereograms similar to the one shown in 
figure 5. Only one subject is identified on each 
stereogram. The stereograms are organized ac- 
cording to the landform on which each is 
found and on gross similarities of image. These 
are regularly consulted during the interpreta- 
tion process, and unknown images are com- 
pared with similar stereograms. We hope to 
develop a dichotomous key to aid in the use of 
these stereograms and where possible the dis- 
crimination of similar images. 
By using these kinds of aids, we have devel- 
oped a reasonably efficient photo interpretation 
procedure. This utilizes a magnifying mirror 
stereoscope and a scanning board that permits 
movement of the stereo model under the field 
of view and arranges other materials for ready 
reference (fig. 6). 
A REMOTE SENSING APPROACH TO 
RANGE RESOURCE ANALYSIS 
Part of the flow chart outlining the major 
steps in our resource analysis project for the 
Oregon State Land Board is presented in figure 
7. The complete flow chart covers four pages 
and contains much more detail, but the one il- 
lustrated is sufficient to indicate the maximum 
level of dependence on aerial photo interpreta- 
tion in the acquisition of useful information 
for the multiple-use management of range re- 
source areas. Note that the procedure is, in ef- 
fect, a double sampling approach. An initial 
10-percent sample of the project area was 
drawn to use in developing both the ecological 
legend and the photo interpretation keys and 
aids. With these available, we conducted the 
project survey by photo interpretation and im- 
plemented it by additional ground checking. 
We have developed a symbolic legend system 
that clearly distinguishes between those areas 
that have been examined on the ground and 
those that have only been photo interpreted. 
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