mirror of
https://github.com/Brandon-Rozek/website.git
synced 2024-11-13 20:27:29 -05:00
114 lines
No EOL
2.8 KiB
Markdown
114 lines
No EOL
2.8 KiB
Markdown
---
|
|
date: 2022-06-19 19:01:35-04:00
|
|
draft: false
|
|
math: false
|
|
medium_enabled: true
|
|
medium_post_id: 45193055c22d
|
|
tags:
|
|
- GPS
|
|
title: Retreiving GPS data in decimal format from EXIF data in photos
|
|
---
|
|
|
|
For a new feature that I'm cooking up for my website, I need to grab the GPS information from the EXIF data stored in my images. Luckily, `imagemagick`
|
|
comes to our rescue.
|
|
|
|
```bash
|
|
identify -verbose $IMAGE_FILE | grep GPS
|
|
```
|
|
|
|
This will return something like the following:
|
|
```
|
|
exif:GPSAltitude: 1250/100
|
|
exif:GPSAltitudeRef: .
|
|
exif:GPSDateStamp: 2022:06:12
|
|
exif:GPSImgDirection: 137/1
|
|
exif:GPSImgDirectionRef: M
|
|
exif:GPSInfo: 1004
|
|
exif:GPSLatitude: 40/1, 50/1, 1815/100
|
|
exif:GPSLatitudeRef: N
|
|
exif:GPSLongitude: 73/1, 53/1, 3625/100
|
|
exif:GPSLongitudeRef: W
|
|
exif:GPSTimeStamp: 17/1, 32/1, 30/1
|
|
exif:GPSVersionID: ....
|
|
```
|
|
|
|
To request a specific field, for example Latitude:
|
|
```bash
|
|
identify -format "%[EXIF:GPSLatitude]\n" "$IMAGE_FILE"
|
|
```
|
|
|
|
As with the verbose flag, it will return the information in degrees format
|
|
```
|
|
40/1, 50/1, 1815/100
|
|
```
|
|
|
|
The following bash function will take the degrees format and convert
|
|
it to the more common decmial format:
|
|
```bash
|
|
DegreesToDecimal() {
|
|
L0=$(echo "$1" | cut -d "," -f 1)
|
|
L1=$(echo "$1" | cut -d "," -f 2)
|
|
L2=$(echo "$1" | cut -d "," -f 3)
|
|
echo "scale=6;$L0 + $L1/60 + $L2/3600" | bc
|
|
}
|
|
```
|
|
|
|
For example:
|
|
```bash
|
|
LAT=$(identify -format "%[EXIF:GPSLatitude]\n" "$IMAGE_FILE")
|
|
LAT_DEC=$(DegreesToDecimal "$LAT")
|
|
echo "$LAT_DEC"
|
|
```
|
|
will output:
|
|
```
|
|
40.838374
|
|
```
|
|
|
|
We can then package this into a script which will output the latitude, longitude, and altitude (m) of an image in decmial format.
|
|
```bash
|
|
#!/bin/sh
|
|
|
|
set -o errexit
|
|
set -o nounset
|
|
set -o pipefail
|
|
|
|
show_usage() {
|
|
echo "Usage: getLLA.sh [imagefile]"
|
|
exit 1
|
|
}
|
|
|
|
# Check argument count
|
|
if [ "$#" -ne 1 ]; then
|
|
show_usage
|
|
fi
|
|
|
|
# Check that relevant command exist
|
|
if ! command -v identify > /dev/null; then
|
|
echo "Command identify from imagemagick not found. Exiting..."
|
|
fi
|
|
|
|
IMAGE_FILE="$1"
|
|
LAT=$(identify -format "%[EXIF:GPSLatitude]\n" "$IMAGE_FILE")
|
|
LAT_DIR=$(identify -format "%[EXIF:GPSLatitudeRef]\n" "$IMAGE_FILE")
|
|
LON=$(identify -format "%[EXIF:GPSLongitude]\n" "$IMAGE_FILE")
|
|
LON_DIR=$(identify -format "%[EXIF:GPSLongitudeRef]\n" "$IMAGE_FILE")
|
|
ALT=$(identify -format "%[EXIF:GPSAltitude]\n" "$IMAGE_FILE")
|
|
|
|
DegreesToDecimal() {
|
|
L0=$(echo "$1" | cut -d "," -f 1)
|
|
L1=$(echo "$1" | cut -d "," -f 2)
|
|
L2=$(echo "$1" | cut -d "," -f 3)
|
|
echo "scale=6;$L0 + $L1/60 + $L2/3600" | bc
|
|
}
|
|
|
|
LAT_DEC=$(DegreesToDecimal "$LAT")
|
|
LON_DEC=$(DegreesToDecimal "$LON")
|
|
ALT_DEC=$(echo "scale=6;$ALT" | bc)
|
|
|
|
LAT_PREFIX=$([ $LAT_DIR == "S" ] && echo "-" || echo "")
|
|
LON_PREFIX=$([ $LON_DIR == "W" ] && echo "-" || echo "")
|
|
|
|
echo "$LAT_PREFIX$LAT_DEC"
|
|
echo "$LON_PREFIX$LON_DEC"
|
|
echo "$ALT_DEC"
|
|
``` |