marcorealacci/master-degree-notes
1
0
Fork 0
Code Issues Pull requests Projects Releases Packages Wiki Activity Actions

vault backup: 2025-01-12 21:43:10

Browse source
This commit is contained in:
Marco Realacci 2025-01-12 21:43:10 +01:00
parent 8d1be3fedd
commit 660bc89ac8
3 changed files with 63 additions and 24 deletions
Download patch file Download diff file Expand all files Collapse all files

4
Biometric Systems/notes/11. Fingerprints.md
View file

@ -113,7 +113,7 @@ The local orientation of the ridge line in the position [i, j] is defined as the
##### Frequency map
the frequency of the local ridge line $f_{xy}$ at the point $[x, y]$ is defined as the number of ridges per unit length along a hypothetical segment centered at $[x, y]$ and orthogonal to the orientation of the local ridge.
- by estimating the frequency in discrete locations arranged in a grid, we can compute a frequency image F:![[Pasted image 20241127225853.png]]
- a possible approach is to count the averaage number of pixels between consecutive peaks of gray levels along the direction orthogonal to the local orientation of the ridge line
- a possible approach is to count the average number of pixels between consecutive peaks of gray levels along the direction orthogonal to the local orientation of the ridge line
##### Singularities
Most of approaches are based on directional map.
@ -161,7 +161,7 @@ Hybrid method based on comparison of minutiae texture: combines the representati
- rotation parameter is the average of rotation of all the individual pairs of corresponding minutiae
- translation parameters are calculable using spatial coordinates of the pair of reference minutiae which produced the best alignment
##### Masking and tesselation
##### Masking and tessellation
After masking the background, the images are normalized by building on them a grid that divides them into series of non-overlapping windows of the same size. Each window is normalized with reference to a constant mean and variance. Optimal size for 300 DPI is 30x30, as 30 pixel is the average distance inter-solco.
![[Pasted image 20241128000431.png]]

3
Biometric Systems/notes/7. Face recognition 3D.md
View file

@ -96,7 +96,8 @@ si possono usare i landmark
2. allineando facce minimizzando la distanza tra punti corrispondenti
##### Fine
Algoritmo ICP
Algoritmo ICP (Iterative Closest Point)
https://www.youtube.com/watch?v=QWDM4cFdKrE
Date due superfici 3D
1. trova un iniziale match tra le due (mapping di punti/superfici/linee/curve)
2. calcola la distanza tra le superfici con il metodo least squares