Forest cover mask from historical topographic maps based on image processing

U Gimmi,K Ostafin,M Iwanowski,D Kaim,C Ginzler,K Ostapowicz,A Cacko,A Psomas,J Kozak

doi:10.1002/gdj3.46

Abstract

This study aimed to obtain accurate binary forest masks which might be directly used in analysis of land cover changes over large areas. A sequence of image processing operations was conceived, parameterized and tested using various topographic maps from mountain areas in Poland and Switzerland. First, the input maps were filtered and binarized by thresholding in Hue‐Saturation‐Value colour space. The second step consisted of a set of morphological image analysis procedures leading to final forest masks. The forest masks were then assessed and compared to manual forest boundary vectorization. The Polish topographical map published in the 1930s showed low accuracy which could be attributed to methods of cartographic presentation used and degradation of original colour prints. For maps published in the 1970s, the automated forest extraction performed very well, with accuracy exceeding 97%, comparable to accuracies of manual vectorization of the same maps performed by nontrained operators. With this method, we obtained a forest cover mask for the entire area of the Polish Carpathians, easily readable in any Geographic Information System software.

Highlights

Historical maps are the only or main reliable source of spatial information on land use and land cover in the past (Kaim et al, 2014; Munteanu et al, 2014; Bu€rgi et al, 2015; Fuchs et al, 2015)
Geoscience Data Journal published by Royal Meteorological Society and John Wiley & Sons Ltd
We develop and test an approach of semiautomatic forest cover extraction tested for three various sets of topographic maps, created in different conditions and cartographic traditions

Summary

Introduction

Historical maps are the only or main reliable source of spatial information on land use and land cover in the past (Kaim et al, 2014; Munteanu et al, 2014; Bu€rgi et al, 2015; Fuchs et al, 2015). Their comparison to current land use and land cover data gives a possibility to study environmental changes in long time horizon (Yang et al, 2014).

Objectives

Results

Discussion

Conclusion