How to find gps cordinates of an object.

[Niladri Puhan]

Hi Friends,
I am using a dji phantom to capture images from different heights. Also I can extract the exif file and see all the drone parameters. Suppose I want to find the longitude and latitude of an object in the image, any resources available either in code or papers?
I implemented few papers, the error is too high. Thanks in advance.

-NBP

 

[hansenn]

You can use a navigation app. Open its map and click on the object/lokation.

 

[Meta4]

I am using a dji phantom to capture images from different heights. Also I can extract the exif file and see all the drone parameters. Suppose I want to find the longitude and latitude of an object in the image, any resources available.

The GPS data in the exif info is the location of the drone when the photo was taken.
If you have the camera pointing straight down, it will show the location data for the centre of the pic.
But if you don't have the camera pointing straight down, finding the location of objects in the image is much more complicated.

 

[Niladri Puhan]

The GPS data in the exif info is the location of the drone when the photo was taken.
If you have the camera pointing straight down, it will show the location data for the centre of the pic.
But if you don't have the camera pointing straight down, finding the location of objects in the image is much more complicated.

Actually, it is for general case of drone and camera orientation...assuming that we are not using map...

 

[Felix le Chat]

If it's an obvious landmark (large boulder, built structure etc.) look at the location data shown in the image editor metadata tab, then cross reference it by finding the same object with Google earth, hover the pointer over the object and take a look in the bottom right corner of the app screen.

 

[bobmacd]

Old Polynesian sailors used to find the proper overhead star by lying in a canoe while the canoe was rotated.

You could achieve the same technological advantage with the camera pointed straight down and rotating the drone to see where the centre of your image lies.

 

[Mark_Y]

Try OpenAthena app from the app store. It lets you pick out an object from you drone photo and identity its GPS location. I don't know if the app is available for Androd but I use it on an iphone.

 

[dave canada]

You can use a navigation app. Open its map and click on the object/lokation.

if I,m using litchi does that count as a navigation app becuase i also need to get corrdinates of an object that is found in a video after the fact

 

[hank970]

If the ground were level, if you knew the precise coordinates of the drone's location, and if the exact altitude (AGL) of the drone and the downward tilt in degrees of the gimbal were known, then all you'd have to do to determine distance from drone to subject would be a simple trigonometry exercise -- solving a right triangle. But that's a lot of "ifs," and it would yield only distance information. You'd also have to know the azimuth of the camera's optical axis when aimed at the subject. Unfortunately, even if you were able to determine distance and knew the azimuth, there's no reliable way to correlate linear measure and angular relationships with lat/long.

Because lines of longitude converge toward the poles, the distance subtended by a degree of longitude varies with latitude. Lat/long may be useful for mariners trying to determine the approximate location of a ship at sea, but for precise measurements on the ground, it's useless. Thus, even if you knew the precise lat/long coordinates of the drone's position, and the precise horizontal distance from drone to subject, you couldn't use that information to determine the precise lat/long of the subject.

Reliance on UTMs (Universal Transverse Mercator) is better because coordinates are expressed in terms of meters north and south of the Equator and east and west from fixed references in each of the sixty bands which combine to encircle the Earth. The distance between any two nearby points expressed in terms of UTMs can be determined via the Pythagorean theorem.

I use UTMs to describe the location and areal extent of archaeological sites and the distance between the loci of nearby sites. Any hand-held GPS receiver (like Garmin, for example) allows users to use UTMs or to toggle between UTMs and lat/long. I don't know if any phone GPS apps or DJI offer that capability.

Assuming that you're in compliance with VLOS requirements, then it should be a simple matter to walk a short distance to the subject and record its location with a phone app or hand-held GPS receiver. If there's a river or other obstacle in the way which precludes a causal stroll, then look for the nearest bridge.

 

[dave canada]

If the ground were level, if you knew the precise coordinates of the drone's location, and if the exact altitude (AGL) of the drone and the downward tilt in degrees of the gimbal were known, then all you'd have to do to determine distance from drone to subject would be a simple trigonometry exercise -- solving a right triangle. But that's a lot of "ifs," and it would yield only distance information. You'd also have to know the azimuth of the camera's optical axis when aimed at the subject. Unfortunately, even if you were able to determine distance and knew the azimuth, there's no reliable way to correlate linear measure and angular relationships with lat/long.

Because lines of longitude converge toward the poles, the distance subtended by a degree of longitude varies with latitude. Lat/long may be useful for mariners trying to determine the approximate location of a ship at sea, but for precise measurements on the ground, it's useless. Thus, even if you knew the precise lat/long coordinates of the drone's position, and the precise horizontal distance from drone to subject, you couldn't use that information to determine the precise lat/long of the subject.

Reliance on UTMs (Universal Transverse Mercator) is better because coordinates are expressed in terms of meters north and south of the Equator and east and west from fixed references in each of the sixty bands which combine to encircle the Earth. The distance between any two nearby points expressed in terms of UTMs can be determined via the Pythagorean theorem.

I use UTMs to describe the location and areal extent of archaeological sites and the distance between the loci of nearby sites. Any hand-held GPS receiver (like Garmin, for example) allows users to use UTMs or to toggle between UTMs and lat/long. I don't know if any phone GPS apps or DJI offer that capability.

Assuming that you're in compliance with VLOS requirements, then it should be a simple matter to walk a short distance to the subject and record its location with a phone app or hand-held GPS receiver. If there's a river or other obstacle in the way which precludes a causal stroll, then look for the nearest bridge.

lucky we arn,t using loran