Article Large Area Forest Yield Estimation with Pushbroom Digital Aerial Photogrammetry Jacob Strunk 1,*, Petteri Packalen 2, Peter Gould 3, Demetrios Gatziolis 4, Caleb Maki 5, Hans-Erik Andersen 6 and Robert J. McGaughey 6 1 USDA Forest Service Pacific Northwest Research Station, 3625 93rd Ave SW, Olympia, WA 98512, USA 2 School of Forest Sciences, Faculty of Science and Forestry, University of Eastern Finland, P.O. Box 111, 80101 Joensuu, Finland;
[email protected] 3 Washington State Department of Natural Resources, P.O. Box 47000 and 1111 Washington Street SE Olympia, WA 98504-7000, USA;
[email protected] 4 USDA Forest Service Pacific Northwest Research Station, 620 Southwest Main Suite 400 Portland, OR 97205, USA;
[email protected] 5 Washington State Department of Natural Resources, P.O. Box 47000, 1111 Washington Street SE Olympia, WA 98504-7000, USA;
[email protected] 6 USDA Forest Service Pacific Northwest Research Station, University of Washington, P.O. Box 352100, Seattle, WA 98195-2100, USA;
[email protected] (H.-E.A.);
[email protected] (R.J.M.) * Correspondence:
[email protected] Received: 5 February 2019; Accepted: 1 May 2019; Published: 7 May 2019 Abstract: Low-cost methods to measure forest structure are needed to consistently and repeatedly inventory forest conditions over large areas. In this study we investigate low-cost pushbroom Digital Aerial Photography (DAP) to aid in the estimation of forest volume over large areas in Washington State (USA). We also examine the effects of plot location precision (low versus high) and Digital Terrain Model (DTM) resolution (1 m versus 10 m) on estimation performance.