{"id":24631,"date":"2012-10-23T10:53:00","date_gmt":"2012-10-23T10:53:00","guid":{"rendered":"http:\/\/www.labri.fr\/perso\/barla\/blog\/?p=24631"},"modified":"2018-05-03T09:06:56","modified_gmt":"2018-05-03T09:06:56","slug":"material-appearance","status":"publish","type":"post","link":"https:\/\/www.labri.fr\/perso\/barla\/blog\/?p=24631","title":{"rendered":"(Un)natural materials"},"content":{"rendered":"<p id=\"top\" \/>Owing to evolution, the way materials are perceived should a priori be adapted to the human scale range. This implies that a same material will ellicit a variety of percepts from different viewpoints, but that these percepts should be sufficiently tied together to give a coherent percept when getting away or closer to the object under inspection.<\/p>\n<p>In this context, visible macro-structures may be entirely part of a material provided they repeat with sufficient similarity accross a base surface. When seen from a distant viewpoint, they will subtly modify material appearance; when seen from a close viewpoint, they will appear as independent shape chunks that nevertheless belong to an underlying appearance pattern; when seen from viewpoints in between these extremes, they will appear as characteristic (although sometimes subtle) perturbations of this same appearance pattern.<\/p>\n<p>In extreme viewpoint conditions, the mechanisms responsible for material perception might be triggered as in &#8220;natural&#8221; conditions, but this time delivering percepts far from veridical. An extremely distant object like the moon will appear as a smooth sphere with a sub-lambertian material to us, although it is in reality crippled with impacts and made of minerals; the canopy of a forest seen from high altitudes will appear as a smooth undulated surface with a moderately glossy material, although it is composed of millions of highly glossy leaves in various orientations. The same percepts arise with extremely close views, like images obtained with micro-scopes: our visual system can do nothing but try to inperpret cellular shapes as made of some material, soft or hard even if it makes no sense to imagine how they would feel to the touch.<\/p>\n<p>There will likely be no intermediate material perception between extreme (unnatural) and natural views, as opposed to multiple scales of a material in a natural range of views. In many common cases, material perception comes close enough to physical properties of objects; on some occasions, material percepts are substituted to properties of objects with imagined shapes; and in most cases, no material perception is at work and all that we&#8217;re concerned with is colors and shadows.<\/p>\n","protected":false},"excerpt":{"rendered":"<p>Owing to evolution, the way materials are perceived should a priori be adapted to the human scale range. This implies that a same material will ellicit a variety of percepts from different viewpoints, but that these percepts should be sufficiently tied together to give a coherent percept when getting away or closer to the object &#8230; <a title=\"(Un)natural materials\" class=\"read-more\" href=\"https:\/\/www.labri.fr\/perso\/barla\/blog\/?p=24631\" aria-label=\"Read more about (Un)natural materials\">Read more<\/a><\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[651],"tags":[],"class_list":["post-24631","post","type-post","status-publish","format-standard","hentry","category-thoughts"],"_links":{"self":[{"href":"https:\/\/www.labri.fr\/perso\/barla\/blog\/index.php?rest_route=\/wp\/v2\/posts\/24631","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.labri.fr\/perso\/barla\/blog\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.labri.fr\/perso\/barla\/blog\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.labri.fr\/perso\/barla\/blog\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.labri.fr\/perso\/barla\/blog\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=24631"}],"version-history":[{"count":7,"href":"https:\/\/www.labri.fr\/perso\/barla\/blog\/index.php?rest_route=\/wp\/v2\/posts\/24631\/revisions"}],"predecessor-version":[{"id":39696,"href":"https:\/\/www.labri.fr\/perso\/barla\/blog\/index.php?rest_route=\/wp\/v2\/posts\/24631\/revisions\/39696"}],"wp:attachment":[{"href":"https:\/\/www.labri.fr\/perso\/barla\/blog\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=24631"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.labri.fr\/perso\/barla\/blog\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=24631"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.labri.fr\/perso\/barla\/blog\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=24631"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}