human/demo/facematch/README.md

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# Human Face Recognition & Matching
- **Browser** demo: `index.html` & `facematch.js`:
Loads sample images, extracts faces and runs match and similarity analysis
- **NodeJS** demo `node-match.js` and `node-match-worker.js`
Advanced multithreading demo that runs number of worker threads to process high number of matches
- Sample face database: `faces.json`
<br>
## Browser Face Recognition Demo
- `demo/facematch`: Demo for Browsers that uses all face description and embedding features to
detect, extract and identify all faces plus calculate simmilarity between them
It highlights functionality such as:
- Loading images
- Extracting faces from images
- Calculating face embedding descriptors
- Finding face similarity and sorting them by similarity
- Finding best face match based on a known list of faces and printing matches
<br>
## NodeJS Multi-Threading Match Solution
### Methods and Properties in `node-match`
- `createBuffer`: create shared buffer array
single copy of data regardless of number of workers
fixed size based on `options.dbMax`
- `appendRecord`: add additional batch of descriptors to buffer
can append batch of records to buffer at anytime
workers are informed of the new content after append has been completed
- `workersStart`: start or expand pool of `threadPoolSize` workers
each worker runs `node-match-worker` and listens for messages from main thread
can shutdown workers or create additional worker threads on-the-fly
safe against workers that exit
- `workersClose`: close workers in a pool
first request workers to exit then terminate after timeout
- `match`: dispach a match job to a worker
returns first match that satisfies `minThreshold`
assigment to workers using round-robin
since timing for each job is near-fixed and predictable
- `getDescriptor`: get descriptor array for a given id from a buffer
- `fuzDescriptor`: small randomize descriptor content for harder match
- `getLabel`: fetch label for resolved descriptor index
- `loadDB`: load face database from a JSON file `dbFile`
extracts descriptors and adds them to buffer
extracts labels and maintains them in main thread
for test purposes loads same database `dbFact` times to create a very large database
`node-match` runs in a listens for messages from workers until `maxJobs` have been reached
### Performance
Linear performance decrease that depends on number of records in database
Non-linear performance that increases with number of worker threads due to communication overhead
- Face dataase with 10k records:
> threadPoolSize: 1 => ~60 ms / match job
> threadPoolSize: 6 => ~25 ms / match job
- Face database with 50k records:
> threadPoolSize: 1 => ~300 ms / match job
> threadPoolSize: 6 => ~100 ms / match job
- Face database with 100k records:
> threadPoolSize: 1 => ~600 ms / match job
> threadPoolSize: 6 => ~200 ms / match job
### Example
> node node-match
```js
2021-10-13 07:53:36 INFO: options: { dbFile: './faces.json', dbMax: 10000, threadPoolSize: 6, workerSrc: './node-match-worker.js', debug: false, minThreshold: 0.9, descLength: 1024 }
2021-10-13 07:53:36 DATA: created shared buffer: { maxDescriptors: 10000, totalBytes: 40960000, totalElements: 10240000 }
2021-10-13 07:53:36 DATA: db loaded: { existingRecords: 0, newRecords: 5700 }
2021-10-13 07:53:36 INFO: starting worker thread pool: { totalWorkers: 6, alreadyActive: 0 }
2021-10-13 07:53:36 STATE: submitted: { matchJobs: 100, poolSize: 6, activeWorkers: 6 }
2021-10-13 07:53:38 STATE: { matchJobsFinished: 100, totalTimeMs: 1769, averageTimeMs: 17.69 }
2021-10-13 07:53:38 INFO: closing workers: { poolSize: 6, activeWorkers: 6 }
```