# Salient Building Outline Enhancement and Extraction Using Iterative L0 Smoothing and Line Enhancing

## TL;DR

This paper introduces an iterative L0 smoothing and line enhancement method for extracting salient building outlines from consumer camera images, addressing weak outlines and over-smoothing issues.

## Contribution

It proposes a novel iterative approach combining L0 smoothing and line enhancement with semantic segmentation filtering for improved building outline extraction.

## Key findings

- Effective enhancement of building outlines in images.
- Improved detection of straight building edges.
- Validated on a new evaluation dataset.

## Abstract

In this paper, our goal is salient building outline enhancement and extraction from images taken from consumer cameras using L0 smoothing. We address weak outlines and over-smoothing problem. Weak outlines are often undetected by edge extractors or easily smoothed out. We propose an iterative method, including the smoothing cell and sharpening cell. In the smoothing cell, we iteratively enlarge the smoothing level of the L0 smoothing. In the sharpening cell, we use Hough Transform to extract lines, based on the assumption that salient outlines for buildings are usually straight, and enhance those extracted lines. Our goal is to enhance line structures and do the L0 smoothing simultaneously. Also, we propose to create building masks from semantic segmentation using an encoder-decoder network. The masks filter out irrelevant edges. We also provide an evaluation dataset on this task.