## My security road

**1. The Canopies Approach**

- Two distance metrics
- First pass
- very inexpensive distance metric
- create overlapping canopies

- Second pass
- expensive, accurate distance metric
- canopies determine which distances calculated

**2. Using Canopies**

- Calculate expensive distances between points in the same canopy
- All other distances default to infinity
- Use finite distances and iteratively merge closest

**3. Preserve Good Clustering**
- Small, disjoint canopies
- Large, overlapping canopies
- original accurate clustering

- Goal: fast and accurate
- For every cluster, there exists a canopy such that all points in the cluster are in the canopy