Brute-force (Bf) Feature Matcher

Bf matcher takes the descriptor of one feature in first set and is matched with all other features in second set and the closest one is returned.

API Syntax

template <int PU = 1, int MAX_KEYPOINTS = 10000>
void bfMatcher(ap_uint<256> desc_list_q[MAX_KEYPOINTS],
               ap_uint<256> desc_list_t[MAX_KEYPOINTS],
               ap_int<16> match_list[MAX_KEYPOINTS],
               ap_uint<32> num_keypoints_q,
               ap_uint<32> num_keypoints_t,
               float ratio_thresh)

Parameter Descriptions

The following table describes template paramters and arguments of the function.

Table 288 Table brute-force matcher Parameter Description
Parameter	Description
PU	Parallel units / compute units. Number of parallel matches computed. Default is ‘1’. Increasing this parameter results in lesser compute time, but also consumes more hardware resources.
MAX_KEYPOINTS	Maximum keypoints in the query and training feature sets.
desc_list_q	Feature descriptor query list of 256-bit type.
desc_list_t	Feature descriptor training list of 256-bit type.
match_list	Index of corresponding matches for query list in training set.
num_keypoints_q	Total number keypoints in the query set. This must not exceed MAX_KEYPOINTS.
num_keypoints_t	Total number keypoints in the training set. This must not exceed MAX_KEYPOINTS.
ratio_thresh	Ratio threshold for lowe’s test, for strong matches.

Resource Utilization

The following table summarizes the resource utilization of the kernel in different configurations, generated using Vitis 2020.2 tool, for MAX_KEYPOINTS of 10000.

Table 289 Table brute-force matcher Resource Utilization Summary
Operating Mode	Operating Frequency (MHz)	Utilization Estimate
Operating Mode	Operating Frequency (MHz)	BRAM_18K	DSP_48Es	FF	LUT
PU = 1	300	162	0	5152	8453
PU = 2	300	176	0	9471	16320
PU = 10	300	176	0	17708	48839

Performance Estimate

The following table summarizes a performance estimate of the kernel in different configurations, as generated using Vitis 2020.2 tool, for MAX_KEYPOINTS of 10000.

Table 290 Table brute-force matcher Function Performance Estimate Summary
Operating Mode	Operating Frequency (MHz)	Latency Estimate Max (ms)
PU = 1	300	333.4
PU = 2	300	168.6
PU = 10	300	34.285

Brute-force (Bf) Feature Matcher - 2023.1 English

Vitis Libraries