Typos, errors, or changes in papers
(from published versions)

 
J. M. Chen and S.G. Leblanc.
A Four-Scale Bidirectional Reflectance Model Based on Canopy Architecture.

(IEEE TGARS, 1997, vol. 35, pp.1316-1337 )
(1) Equation (34), on page 1322, is not used anymore for the calculation of the mean distance between trees. Instead, the mean distance between trees is calculated more accurately with the gap size distribution:
Pt is the gap size distribution between crown (Equation 47) and l is the gap size. This is more accurate since it depends on the non random distribution of crowns simulated by the Neyman distribution. 
(2) Q1tot and Q2tot: basically, Q1tot  (Eq. 58) now uses the same formulation as Q2tot (Eq. 62). Cv and Cs also have been slighly changed:
(3) Equation (65) should be:
(4) in Equation (45), L =1
S. G. Leblanc, P. Bicheron , J. M. Chen, M. Leroy and J. Cihlar,
Investigation of directional reflectance in boreal forests using an improved 4-Scale model and airborne POLDER Data.

IEEE TGARS,  Vol. 37, No. 3, pp. 1396-1414, May 1999
(1) The Repulsion function (Fo in the papers, but Fr in this manual) has been modified to accomodate more cases:
Fr(q) = FFO*exp(-2q/p(SG(q)-SG(q=0))/SG(q=0))
where FFO is the input repulsion parameter, q is the view or solar zenith angle, SG is the projection of one crown on the ground at the angle  q.
Wrong graphs for Figure 9 (e) and (f) on page 1407, they should be:
S. G. Leblanc, J. M. Chen and J. Cihlar,
    Directionality of NDVI in Boreal Forest: A Model Simulation of Measurements"
    Canadian Journal Remote Sensing, Vol. 23, No. 4, 
    December 1997, pp. 369-380.
 
On page 375, some of the shaded reflectivities miss "Z" in the subscripts.