There are several methods which can be used to measure a crop's 
acreage in a scene. Techniques and procedures which have been 
developed and tested in LACIE operations or in its research and devel- 
opment programs have been used by USDA analysts to estimate crop 
acreages. An effort was made by the analysts to develop procedural 
and processing alternatives relative to different wheat growing 
regions and variations in cultural/cropping practices in several 
countries. Each of the examples presented support a hypothesis that 
analyst perceived conditions by region and year dictate the multi- 
spectral analysis decision logic. 
II. Conditions Encountered in Landsat Analysis 
User goals also dictate to a great extent what type of operational 
environment must be established in order to perform the required 
analysis. Remote Sensing analysis demands that there exists an 
integrated procedure for utilizing personnel and equipment in an 
efficient manner. Equipment and personnel have to compliment each 
other in order to establish a set of processing procedures which 
are needed to perform the required spectral data analysis. It is 
advantageous to use electronic data processing equipment to analyze 
conditions which are fixed in a scene and are repeated from year 
to year. Conversely, the variable conditions and characteristics 
are more conducive to analyst interpretation. It is therefore 
necessary to group scene characteristics into those which are vari- 
able and those which are fixed. Those scene characteristics which 
are fixed should be used as a guideline in developing procedures to 
handle the various fixed attributes. In addition to a perceived 
methodology for exploiting Landsat data, its practical utility 
depends upon agricultural considerations, available processing tech- 
niques and finally the optimum merging of considerations and techniques. 
A. Agricultural Considerations 
Each year farmers decisions both fixed and variable are represented 
in remotely sensed Landsat data. Within agriculture there are many 
conditions which exist that force farmers to choose between various 
alternatives in order to maximize their return. One of the most 
dominant factors farmers have to consider are the existing climatic 
conditions. This factor strongly effects which crops a farmer can, 
or will choose to plant. However, the farmers also have to take into 
consideration factors such as soil type, topographic conditons, plant 
varieties, property lines, fertilization practices, and economic 
conditions. All such factors give the farmer choices in three areas: 
what to plant, how much to plant and how to care for what is planted. 
It is primarily the results of the first two choices, what and how 
much to plant, which can be seen on the Landsat images. The various 
plant types can be distinguished by nominal planting and harvesting 
dates, and identifying the spectral history of the crop through the 
season. The problem of identifying crop types is closely related to 
  
   
   
     
     
     
    
    
    
   
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