STEREO-PHOTO TECHNIQUE 



The stereo pairs were taken of each tree 

 bole from the four cardinal directions with a 

 Crown Graphic camera 1 mounted on a slide 

 base. Each photograph included at least the 

 butt 33-foot section of the tree bole. A 

 metal telescoping measuring pole marked in 

 1-foot intervals was used to determine heights 

 (Fig. 1). 



Stereo pairs were analyzed in the office 

 using a pocket stereoscope. Tree boles were 

 examined to a height of 17.3 feet. The quality 

 classification system (Sonderman and Brisbin 

 1978) was used to measure and record the 

 quality -related variables from each tree. 

 The following variables were measured and 

 recorded: 



1. The number of primary limbs on each 

 8-foot section of the lower 16 feet of the 

 tree bole. Only limbs > 1/3 inch were 

 counted and tallied by live and dead cate- 

 gories. 



2. The size of the single largest live and 

 dead limb for each 8-foot section. Only 

 limbs > 1/3 inch were recorded. The diam- 

 eter of the measuring pole was used to esti- 

 mate limb size. 



3. Stem curvature was estimated in inches 

 for the butt 16-foot section of each tree. 



4. The number and extent of defect indi- 

 cators (rots and seams) in the butt 16-foot 

 section of the tree bole. 



5. The number of epicormic branches in 

 each 8-foot section of the butt 16-foot por- 

 tion of the tree. 



6. The number of measurable overgrowths 

 (Sonderman 1979) in each 8-foot section of 

 the tree bole. 



7. The height, in feet, of the first fork in 

 the butt 16-foot section of the tree bole. 



Total height, crown class, crown ratio, and 

 dbh were determined each time the trees 

 were photographed. 



The use of trade, firm, or corporation names 

 in this publication is for the information and con- 

 venience of the reader. Such use does not constitute 

 an official endorsement or approval by the U.S. 

 Department of Agriculture or the Forest Service 

 of any product or service to the exclusion of others 

 that may be suitable. 



Figure 1.— Stereo pair. 



2 



