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anchorgenerator

anchorgenerator

Module for the anchorgenerator

Classes

AnchorGenerator

Class for generating anchors for object detection

Functions
gen_anchors_for_featuremap 
gen_anchors_for_featuremap(
    image_size,
    scale,
    aspect_ratios,
    anchor_scales,
    base_area_side,
)

Generates anchors for one featuremap

Source code in niceml/mlcomponents/objdet/anchorgenerator.py 
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def gen_anchors_for_featuremap(  # pylint: disable=too-many-locals,too-many-arguments
    self,
    image_size: ImageSize,
    scale: int,
    aspect_ratios: List[float],
    anchor_scales: List[float],
    base_area_side: float,
) -> List[BoundingBox]:
    """Generates anchors for one featuremap"""

    steps_width = image_size.width // scale
    steps_height = image_size.height // scale
    area: float = (base_area_side * scale) ** 2

    width_height_list = calculate_anchor_width_height_list(
        aspect_ratios, anchor_scales, area
    )
    bbox_list: List[BoundingBox] = []
    for y_pos in range(steps_height):
        for x_pos in range(steps_width):
            center_x = (x_pos + 0.5) * scale
            center_y = (y_pos + 0.5) * scale
            for cur_width, cur_height in width_height_list:
                bounding_box: BoundingBox = bounding_box_from_absolute_cxcywh(
                    center_x, center_y, cur_width, cur_height
                )
                bbox_list.append(bounding_box)
    return bbox_list
generate_anchors 
generate_anchors(data_description)

Generate anchors for all feature maps and appends them

Source code in niceml/mlcomponents/objdet/anchorgenerator.py 
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def generate_anchors(
    self, data_description: OutputObjDetDataDescription
) -> List[BoundingBox]:
    """Generate anchors for all feature maps and appends them"""
    out_anchors = []
    for feature_map_scale in data_description.get_featuremap_scales():
        out_anchors += self.gen_anchors_for_featuremap(
            image_size=data_description.get_input_image_size(),
            scale=feature_map_scale,
            aspect_ratios=data_description.get_anchor_aspect_ratios(),
            anchor_scales=data_description.get_anchor_scales(),
            base_area_side=data_description.get_base_area_side(),
        )
    return out_anchors

Functions

calculate_anchor_width_height_list 

calculate_anchor_width_height_list(
    aspect_ratios, anchor_scales, area
)

calculates the widths and heights for one featuremap

Source code in niceml/mlcomponents/objdet/anchorgenerator.py 
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def calculate_anchor_width_height_list(
    aspect_ratios: List[float], anchor_scales: List[float], area: float
) -> List[Tuple[float, float]]:
    """calculates the widths and heights for one featuremap"""
    width_height_list = []
    for cur_ratio in aspect_ratios:
        anchor_height = sqrt(area / cur_ratio)
        anchor_width = area / anchor_height
        for cur_scale in anchor_scales:
            width_height_list.append(
                (anchor_width * cur_scale, anchor_height * cur_scale)
            )

    return width_height_list