added model changes notes

Models.md

@@ -13,14 +13,39 @@ Default models in Human library are:
 - **Hand Analysis**: MediaPipe Hands
 - **Object Detection**: MobileNet-v3 with CenterNet
 
-## Notes
+<br>
+
+## Changes
+
+All models are modified from original implementation in following manner:
+
+- Input pre-processing: image enhancements, normalization, etc.
+- Caching: custom caching operations to bypass specific model runs when no changes are detected
+- Output parsing: custom analysis of HeatMaps to regions, output values normalization, etc.
+- Output interpolation: custom smoothing operations
+- Model modifications:
+  - Model definition: reformatted for readability, added conversion notes and correct signatures
+  - Model weights: quantized to 16-bit float for size reduction
+
+Models are not re-trained so any bias included in the original models is present in `Human`  
+*For any possible bias notes, see specific model cards*  
+
+<br>
+
+## Using Alternatives
+
+`Human` includes implementations for several alternative models which are normally not 1:1 replacement,  
+but can be switched on-the-fly due to standardized output implementation
+
+<br>
 
 **Body detection** can be switched from `PoseNet` to `BlazePose`, `EfficientPose` or `MoveNet` depending on the use case:
 
 - `PoseNet`: Works with multiple people in frame, works with only partial people  
   Best described as works-anywhere, but not with great precision
-- `MoveNet`: Works with single person in frame, works with only partial people  
+- `MoveNet-Lightning`: Works with single person in frame, works with only partial people  
   Modernized and optimized version of PoseNet with different model architecture
+- `MoveNet-Thunder`: Variation of `MoveNet` with higher precision but slower processing
 - `EfficientPose`: Works with single person in frame, works with only partial people  
   Experimental model that shows future promise but is not ready for wide spread usage due to performance
 - `BlazePose`: Works with single person in frame and that person should be fully visibile  
@@ -33,6 +58,8 @@ Default models in Human library are:
 - `Age Detection`: SSR-Net Age IMDB
 - `Face Embedding`: BecauseofAI MobileFace Embedding
 
+**Object detection** can be switched from `mb3-centernet` to `nanodet`
+
 <br><hr><br>
 
 ## List of all models included in Human library