Bosporus Strait and Istanbul, Turkey : The Bosporus is a strait that connects the Black Sea, at the top of the image, with the Sea of Marmara in the center of this view of northwest Turkey, taken during the Shuttle Radar Topography Mission (SRTM) in February 2000; original data resolution: 1 arcsecond (about 30 meters). Three visualization methods were combined to produce this image: shading and color coding of topographic height and radar image intensity. The shade image was derived by computing topographic slope in the northwest-southeast direction; northwest-facing slopes appear dark and southeast-facing slopes appear bright. Color coding is directly related to topographic height, with green at the lower elevations, rising through yellow and brown to white at the highest elevations. The shade image was combined with the radar intensity image to add detail, especially in the flat areas. The water of the Black Sea and Sea of Marmara  are colored blue in this image, along with several large lakes. The Bosporus (Turkish Bogazici) Strait is considered to be the boundary between Europe and Asia, and the large city of Istanbul is located on both sides of the southern end of the strait, visible as a brighter (light green to white) area on the image due to its stronger reflection of radar.