Accuracy of Reconstruction with Short baseline from a Single-frame Multispectral Camera

Abstract. Close-range acquisition of multispectral images is becoming widespread in many applications, such as forestry and agriculture monitoring. However, some challenges still need to be addressed, such as the co-registration of the spectral bands generated with multi-lens cameras. Depth variations can introduce differential parallax effects depending on the lens position, which makes the coregistration more challenging. Therefore, a rigorous registration of this multispectral imagery requires pixel-wise parallax compensation, based on a depth model. This work presents a detailed evaluation of the accuracy of depth estimation with images acquired from a single-frame camera with a very short baseline. The methodology involves accurate camera calibration and three-dimensional reconstruction using Agisoft Metashape software. Field validation was conducted using a high-resolution laser scanner to produce reference data. Results show that even a single image frame, composed of six sub-images from different lenses, enables 3D reconstruction with reasonable (centimetre) accuracy, while a full image set achieves sub-centimetre accuracy. Comparison with a laser scanner reference point cloud showed the spatial consistency of the reconstructed surface. The results demonstrate the viability of reconstruction with short baseline images, aiming for pixel-wise registration.