Emgu CV Library Documentation
hessianThreshold Field
NamespacesEmgu.CV.StructureMCvSURFParamshessianThreshold

www.emgu.com/wiki
Only features with keypoint.hessian larger than that are extracted. good default value is ~300-500 (can depend on the average local contrast and sharpness of the image). user can further filter out some features based on their hessian values and other characteristics
Declaration Syntax
C#Visual BasicVisual C++
public double hessianThreshold
Public hessianThreshold As Double
public:
double hessianThreshold

Assembly: Emgu.CV (Module: Emgu.CV) Version: 1.5.0.0 (1.5.0.0)