[TOC] ## 概況 ### Background:把照片放在地圖上 我使用的Nokia Lumia 920沒有一個好的照片應用 ### Showcase  Phodal’s Image ### 框架： EXIF & ExifRead & CartoDB **EXIF** > 可交換圖像文件常被簡稱為EXIF（Exchangeable image file format），是專門為數碼相機的照片設定的，可以記錄數碼照片的屬性信息和拍攝數據。 EXIF信息以0xFFE1作為開頭標記，后兩個字節表示EXIF信息的長度。所以EXIF信息最大為64 kB，而內部采用TIFF格式。 **ExifRead** 來自官方的簡述 > **Python library to extract EXIF data from tiff and jpeg files.** **ExifRead安裝** ~~~ pip install exifread ~~~ **ExifRead Exif.py** 官方寫了一個exif.py的command可直接查看照片信息 ~~~ EXIF.py images.jpg ~~~ **CartoDB** > Create dynamic maps, analyze and build location aware and geospatial applications with your data using the power using the power of PostGIS in the cloud. ## 步驟 ### Step 1: 解析讀取照片信息 簡單的來說，就是我們可以創建包含位置信息的內容到上面去。 主要步驟如下： * 需要遍歷自己的全部圖片文件 * 解析照片信息 * 生成地理信息文件 * 上傳到cartodb **python 遍歷文件** 代碼如下，來自于《python cookbook》 ~~~ import os, fnmatch def all_files(root, patterns='*', single_level=False, yield_folders=False): patterns = patterns.split(';') for path, subdirs, files in os.walk(root): if yield_folders: files.extend(subdirs) files.sort() for name in files: for pattern in patterns: if fnmatch.fnmatch(name, pattern): yield os.path.join(path, name) break if single_level: break ~~~ **python 解析照片信息** 由于直接從照片中提取的信息是 ~~~ [34, 12, 51513/1000] ~~~ 也就是 ~~~ N 34? 13' 12.718 ~~~ 幾度幾分幾秒的形式，我們需要轉換為 ~~~ 34.2143091667 ~~~ 具體的大致就是 ~~~ def parse_gps(titude): first_number = titude.split(',')[0] second_number = titude.split(',')[1] third_number = titude.split(',')[2] third_number_parent = third_number.split('/')[0] third_number_child = third_number.split('/')[1] third_number_result = float(third_number_parent) / float(third_number_child) return float(first_number) + float(second_number)/60 + third_number_result/3600 ~~~ 也就是我們需要將second/60，還有minutes/3600。 **python 提取照片信息生成文件** ~~~ import json import exifread import os, fnmatch from exifread.tags import DEFAULT_STOP_TAG, FIELD_TYPES from exifread import process_file, __version__ def all_files(root, patterns='*', single_level=False, yield_folders=False): patterns = patterns.split(';') for path, subdirs, files in os.walk(root): if yield_folders: files.extend(subdirs) files.sort() for name in files: for pattern in patterns: if fnmatch.fnmatch(name, pattern): yield os.path.join(path, name) break if single_level: break def parse_gps(titude): first_number = titude.split(',')[0] second_number = titude.split(',')[1] third_number = titude.split(',')[2] third_number_parent = third_number.split('/')[0] third_number_child = third_number.split('/')[1] third_number_result = float(third_number_parent) / float(third_number_child) return float(first_number) + float(second_number)/60 + third_number_result/3600 jsonFile = open("gps.geojson", "w") jsonFile.writelines('{\n"type": "FeatureCollection","features": [\n') def write_data(paths): index = 1 for path in all_files('./' + paths, '*.jpg'): f = open(path[2:], 'rb') tags = exifread.process_file(f) # jsonFile.writelines('"type": "Feature","properties": {"cartodb_id":"'+str(index)+'"},"geometry": {"type": "Point","coordinates": [') latitude = tags['GPS GPSLatitude'].printable[1:-1] longitude = tags['GPS GPSLongitude'].printable[1:-1] print latitude print parse_gps(latitude) # print tags['GPS GPSLongitudeRef'] # print tags['GPS GPSLatitudeRef'] jsonFile.writelines('{"type": "Feature","properties": {"cartodb_id":"' + str(index) + '"') jsonFile.writelines(',"OS":"' + str(tags['Image Software']) + '","Model":"' + str(tags['Image Model']) + '","Picture":"'+str(path[7:])+'"') jsonFile.writelines('},"geometry": {"type": "Point","coordinates": [' + str(parse_gps(longitude)) + ',' + str( parse_gps(latitude)) + ']}},\n') index += 1 write_data('imgs') jsonFile.writelines(']}\n') jsonFile.close() ~~~ ### Step 2: 上傳數據 注冊CartoDB，然后上傳數據。 ### 練習建議 無