Digital Analytical Geometry: How do I define a digital analytical object?

International audienceThis paper is meant as a short survey on analytically de-ned digital geometric objects. We will start by giving some elements on digitizations and its relations to continuous geometry. We will then explain how, from simple assumptions about properties a digital object should have, one can build mathematical sound digital objects. We will end with open problems and challenges for the future

Fourier Transform to Detect Pine Seedlings in a Digital Image

Each year, u.s. forest nurseries produce approximately 200 million pine seedlings. Forest companies depend on an adequate number of seedlings in order to replant timber land. To monitor the progress of seedlings, nurseries periodically conduct an inventory. The procedure is performed manually and is based on a statistical estimate. The process is slow, tedious, and imprecise. Automating the inventory procedure is subject of this dissertation. A digital image processing technique to visually count pine seedlings is investigated. The technique is based on a proposed imaging system which resides on a platform behind a tractor. As the system passes over the seedling bed, image sensors capture an overhead view of individual seedlings. A computer analyzes the sensor values in order to detect and count individual seedlings. This dissertation is concerned with developing a computer algorithm. Several test images were obtained. Pertinent seedling features in the images are gray level contrast, lines formed by the needles, and circular distribution of the needles. Four different techniques were investigated in an attempt to use these features to detect pine seedlings. These techniques are gray level peaks geometric intersection of needle lines, gray level contour encoding 1 and a technique based on the Fourier transform.Agricultural Engineerin