advantages, most of which would apply to 
other remote sensing systems: 
1. Pictorial backup for ground treatments 
and measurements. This is the obvious and 
currently the most common use of photography. 
2. A photographic base upon which to make 
measurements similar to on-ground measure- 
ments. For example, line intercept measure- 
ments or shrub distribution maps can be made 
from aerial photographs. 
3. Provide a photographic base for new 
measurements unique to the photograph. An 
example is the measurement of optical density 
of specific imaged objects to relate photo image 
characteristics to species identification or the 
estimation of some vegetation parameters such 
as foliar cover, by means of automatic data 
processing. 
4. Provide a permanent photographic record 
for later examination to evaluate the reasons 
for unsuspected change or reaction of vegeta- 
tion to some factor(s). For example, a small 
colony of annuals, even though unnoticed now, 
is preserved on film for future viewing should 
it become widespread and obvious in later 
years. 
5. Eliminate measurement variation due to 
personnel changes or changing measurement 
standards by allowing today’s photo _ inter- 
preter to return to yesterday’s scene and to 
simultaneously remeasure both situations by 
an identical procedure. 
6. Shorten the season of field data collection 
and partially solve the changing phenology 
problem as it affects measurement of vegeta- 
tion parameters. 
CONCLUSIONS 
Our current efforts have been directed to- 
ward (1) developing identification techniques 
and tests for plant species and other wild land 
features, (2) determining optimum film types 
and dates for taking photos, and (8) perfect- 
ing herbaceous shrub photogrammetry tech- 
niques. Included were preliminary efforts to re- 
late microdensitometer measurements to on- 
ground line-intercept values. 
Many problems have been encountered. More 
intensive ground truth was needed, and will be 
incorporated into future studies. We found it 
very difficult to describe color on the photo- 
graphs, even using Munsell color chips. Thus, 
the description of photo images based on non- 
color characteristics (texture, height, shape, 
shadow, etc.) may be of equal or greater value 
in identification than color descriptors. How- 
ever, the use of color descriptors still offers 
greater potential for identification purposes be- 
cause the color combinations are greater than 
the number of gray tones in panchromatic pho- 
tographs. 
There is need for fundamental research into 
such factors as the physiological causes of dif- 
ferent shades of color of plant species as 
shown on the photographs. There is also a 
need to develop automated interpretation and 
analyses by use of a device such as a scanning 
microdensitometer coupled to a computer sys- 
tem, which would reduce the volume of data in 
the aerial photographs into usable forms. 
Finally, there is need for continued coopera- 
tion and open interchange of ideas and devel- 
opments. This includes contact with scientists 
and others working with the various sensor 
systems. 
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