image might intuitively appear as an act of overprocessing, the result 
(Table 1) was closer to the original than the 'IBIS' technique alone. 
Computer Labeling of Manual Delineations. Automated procedures can be 
used for delineating polygons on satellite data, but the photo inter 
preter is likely to produce a result that needs no post-processing and 
is better suited for management uses. On the other hand, the computer 
can be 'trained' to apply polygon labels that are more accurate and 
consistent than the photo interpreter. Thus, a procedure was developed 
(Woodcock, et al., 1980) to blend the best of human skills and computer 
consistency. This procedure can also double as a raster-to-vector con 
version technique: 1) The polygon boundaries are prepared by the USFS 
using their WRIS vector system; 2) The vector boundaries are converted 
to raster format using standard VICAR/IBIS software; 3) The FOCIS 
stratum map is registered to the polygon map; 4) Labels are assigned to 
each polygon based on a voting rule of the number of classified pixels 
falling within each polygon; and 5) Labels are transfered to WRIS in a 
text format. 
An important advantage of this procedure is that many US National 
Forest (and other management areas) already create polygon delineation 
maps, and many of them are regularly put into machine format. Thus, 
there is little need for an agency to change its standard operating 
procedures or develop a new computer interface. Furthermore, since 
boundaries in natural environments are relatively more stable than 
vegetative labels, the same boundary maps could be used repeatedly with 
little updating and thus better preserve the continuity between subse 
quent stratifications than is typical with raster satellite classifica 
tions . 
The key to the successful use of this procedure is a suitable voting 
rule. Initially, a simple plurality rule was tested. This was found 
wanting, and a new approach was devised. The new label decision 
criterion uses separate voting procedures for each of the three FOCIS 
label components. Each pixel in the stratified image contains label 
distinctions for each of three characteristics: regional type, size, 
and density. Under the plurality decision criterion, the most commonly 
occurring three-part label was assigned to the polygon. In the new 
approach, each component of the label is voted on independently of the 
others and the three winning components are combined to provide the new 
label. For example, consider a polygon containing pixels labeled ac 
cording to the following proportions: 30% M3P, 25% M4P, 25% M4S, and 
20% M4N. In this situation, the label M3P would be assigned under the 
plurality voting rule. However, following close inspection, a size 
class of 3 is not appropriate since 70% of the pixels received a size 
class 4 label. Using the new label decision criterion, a more ap 
propriate label of M4P would be assigned to the stand. The same tech 
nique is applied to all three label components. 
CONCLUSION 
Three different alternatives in post-processing for raster-to-vector 
conversion have been discussed. Selection of the technique best suited 
for a particular application depends on the peculiarities of the ap 
plication. All three techniques employ seme form of simplification, 
but it is more apparent in the spatial filtering approach. 
The Modified Davis and Peet technique best preserves the original 
histogram and experiences the least amount of pixel class conversion. 
However, it permits diagonal connections which are undesirable for