Many smartphones take geotagged photos, but even though now they have cameras that take pretty fine pictures, they can`t be compared with the photos of a DSLR camera. If you have your full ride tracked, you can geotag your pothos later on, using a program to match the time when photos was taken (from the exif data) with the location in your track. GPS systems for bikes are expensive, and I don`t consider them as a solution to log data for the whole tour. The better solution for me seems to be a small device that consumes little power and silently logs gps position.

For that today I downloaded two android apps and tested them on a Samsung Galaxy S. Here are the recorded tracks from both of them.

Open GPS Tracker

Move! Bike Computer

I put my phone in my outside chest pocket, using it in a inside pocked didn`t worked. The Move! Bike Computer recorded a more accurate track but maybe if I played a little more with the settings in Open Gps Tracker I could obtained a more detailed track there also. I think that both programs worked really well, and the results were satisfactory, but the problem is the phones batter life. For about 2 hours riding is consumed 45% of the battery.

Bottom line is that I don`t consider this to be a valid solution if you plan to make rides that would take many days. You need to keep the phone in an outside poket (pants upper pocket also didn`t worked), you will have to charge it alot, take care for the app not to be closed by mistake and so on, I think is to much hustle.

I have ordered the Holux M1200E gps logger. It logs gps data and also can be used as a gps received to be paired with a laptop via bluetooth. More on that when I`ll get a hold on it.

Unfortunately, after uploading few images I discovered that the cool functionality of searching photos with gps exif data and displaying their location on map was not working. That was because the images displayed don`t have any exif data stored in the file, as wordpress automatically  stripes it down on image upload, but not before data is read so it can be stored serialized in postmeta table from db. Instead of altering wordpress core files to modify this behavior, I preferred to find a different approach and try using the meta info already stored into database. But the problem is that wp save only some tags from exif, and GPS information in not among them, so first step is to add the following filter to the wp_read_image_metadata hook:

add_filter('wp_read_image_metadata', 'saveGeoExif','',3);

function saveGeoExif($meta,$file) {
    $exif = @exif_read_data($file);

    if (isset($exif['GPSLatitude'])){
        $meta['GPSLatitude'] = $exif['GPSLatitude'];
    }
    if (isset($exif['GPSLatitudeRef'])){
        $meta['GPSLatitudeRef'] = trim($exif['GPSLatitudeRef']);
    }
    if (isset($exif['GPSLongitude'])){
        $meta['GPSLongitude'] = $exif['GPSLongitude'] ;
    }
    if (isset($exif['GPSLongitudeRef'])){
        $meta['GPSLongitudeRef'] = trim($exif['GPSLongitudeRef']);
    }

    if (isset($exif['GPSAltitudeRef'])){
        $meta['GPSAltitudeRef'] = trim($exif['GPSLongitudeRef']);
    }
    if (isset($exif['GPSAltitude'])){
        $meta['GPSAltitude'] = trim($exif['GPSLongitudeRef']);
    }
    if (isset($exif['GPSTimeStamp'])){
        $meta['GPSTimeStamp'] = $exif['GPSLongitudeRef'];
    }
    if (isset($exif['GPSDOP'])){
        $meta['GPSDOP'] = $exif['GPSLongitudeRef'];
    }
    if (isset($exif['GPSImgDirectionRef'])){
        $meta['GPSImgDirectionRef'] = trim($exif['GPSLongitudeRef']);
    }
    if (isset($exif['GPSImgDirection'])){
        $meta['GPSImgDirection'] = trim($exif['GPSLongitudeRef']);
    }

	return $meta;
}

This will save all GPS information into database upon image upload.

Next we need to search all the photo attachments belonging to a post, calculate their coordinates and extract image url, and then pass them to geotag plugin.

add_filter("the_content", 'getGeodataFromMeta');

function fractionResult($fraction){
    list($sup, $sub) = explode('/', $fraction);
    if(floatval($sub) != 0){
        return $sup / $sub;
    }else{
        return 0;
    }
}

function getCoord($fractional, $ref){
    $coord = 0;
    if(is_array($fractional)){
        $coord = fractionResult($fractional[0]) + fractionResult($fractional[1]) / 60 + fractionResult($fractional[2]) / 3600;
    }
    if($ref == "S" || $ref == "W"){
        $coord = -$coord;
    }
    return $coord;
}

function getGeodataFromMeta($content){
    global $photoMetaCoords;
    $postId = get_the_ID();
    $attachments = get_posts('post_type=attachment&post_mime_type=image&post_parent=' . $postId);

    foreach ($attachments as $attachment){
        $meta = wp_get_attachment_metadata($attachment->ID);
        if(isset($meta['image_meta']['GPSLatitude'])){
            $lat = getCoord($meta['image_meta']['GPSLatitude'], $meta['image_meta']['GPSLatitudeRef']);
            $long = getCoord($meta['image_meta']['GPSLongitude'], $meta['image_meta']['GPSLongitudeRef']);

            $imageUrl = wp_get_attachment_image_src($attachment->ID, array(133, 133));
            $photo = array(
                'lat' => $lat,
                'lon' => $long,
                'uri' => $imageUrl[0]
            );

            $photoMetaCoords[] = $photo;
        }
    }
    return $content;
}

Last thing we need to do in order to get all this to work is to alter a bit geotag plugin, so it will also load the images from $photoMetaCoords array. In function getGeotagsFromPhotos() add the following line before if (empty($geotags)) {return null;} else… :

$geotags = array_merge($geotags, $photoMetaCoords);
$photoMetaCoords = array();

Also at the begining of getGeotagsFromPhotos() function change:

global $post;

to

global $post, $photoMetaCoords;

That`s it!

All the code presented here should be added in functions.php or in geotag.php (except the last line which should always go in geotag.php, of course :) ).

turda

flowers

pfff

var vinletters=new Array();
vinletters[1]="AJ";
vinletters[2]="BKS";
vinletters[3]="CLT";
vinletters[4]="DMU";
vinletters[5]="ENV";
vinletters[6]="FW";
vinletters[7]="GPX";
vinletters[8]="HY";
vinletters[9]="RZ";

//--------------12345678901234567
var vinweight= "8765432T098765432";

function valvin(serie){
	if(serie.length == 17){
		suma = 0;
		for (i=0 ; i < serie.length; i++) {
			nextchar = serie.charAt(i);
			for (j in vinletters){
				if(vinletters[j].indexOf(nextchar) != -1){
					nextchar = j;
				}
			}
			val = parseInt(nextchar);
			weight = vinweight.charAt(i);
			if(weight == "T"){
				weight = 10;
			}else{
				weight = parseInt(weight);
			}
			suma += val * weight;
		}
		controlchar = suma % 11;
		if(controlchar == 10) controlchar = "X";
		if(controlchar == serie.charAt(8)){
			return true;
		}else{
			return false;
		}
	}else{
		return false;
	}
	return false;
}

In 2008 he released a second one.

It really makes me shiver.