Tag Archive: pts

We just had a new beta release for PlanIt! The main enhancement in this beta release is to bring different modes to the viewfinder. In the previous beta release, we used the elevation service to draw the ground contour. While it works, the display is not very attractive. In this release, we improved it using two approachs – use the phone camera to create an augmented reality, and use an existing picture to replace the ground contour. We called the existing ground contour mode – the ViewFinder (VR) mode, the camera AR – ViewFinder (AR) mode, and the picture one – ViewFinder (Picture) mode. All three modes can be selected by clicking on the map icons on the action bar.

Take a look at the three pictures below. You can see the camera location and the scene location in case you would like to try it yourself. I also attached the jpg file I used in this example as well as the .xmd file which is the metadata file used by PlanIt! along with the picture.


The left one is the ViewFinder (VR) mode. As you can see, it shows a contour of the Half Dome but without any other details. The right one is the ViewFinder (Picture) mode. Because it is a real photo, you can see exactly what it would look like at this particular location. Most importantly, you can adjust the time to see the position of celestial objects in the future or in the past using this real photo as background.

device-2014-05-12-200603  device-2014-05-12-200556


If you are at the location, you can also turn on the phone camera to take a picture or use the augmented reality.

You can download the Half Dome photo I used in this post below. The corresponding data associated with this photo is also included below. I strongly encourage you give your own photo a try. Even with the same scene, you can compose it with Sun, Moon, star-trails, or milky way, and to give it a different feeling.

Picture file used by in this post

You also need a .xmd file. Just copy the text below and save it at the same folder as the picture file using the same file name except with “.xmd” at the end. If you save the picture file above as “pic1.jpg”, then save this xml file as “pic1.jpg.xmd”.

“Azimuth”: 84.78215026855469,
“VerticalAngleOfView”: 59.599998474121094,
“HorizontalAngleOfView”: 41.794071197509766,
“Latitude”: 37.74017171039168,
“Longitude”: -119.59974355995654,
“Elevation”: -2.2449021339416504



I never thought I will be doing this but after I finished the implementation the viewfinder feature in the Planit app, it occurred to me. Why not try to date the famous Moon and Half Dome photo using this app?

Here is the original photo by Ansel Adams.


Let’s list the clues we had so far.

  1. Waxing Gibbous moon as we can see.
  2. There was snow on the ground which means it was in winter.
  3. We also know the photo were taken in 1960 and were taken after 3pm in the afternoon as Ansel said it in his Autobioyaphy. But he never mentioned the exact date and the exact time.
  4. The camera location is hard to be exact so we have to try our luck here.  The shadow on the left is the Washington Column. With that in mind, I put the camera at the below location so that the Washington Column is between the camera and the Half Dome.

After studying the map and the picture carefully, see below for where i place the camera icon and the scene icon. You can see the GPS coordinates of both locations below. I verified the camera location is at an open area to the west of the Ahwahnee Hotel so it is possible to get there and have a clear view to the half dome as I’ve been there before. On the screenshot below, the line between the two icons is green which also means there is nothing in between.

device-2014-04-19-224416 device-2014-04-19-222114

Now switch to Finder page, select Waxing Gibbous, select the date to be 1/1/1960 to 12/31/1960.  Now switch to the viewfinder view. The main advantage of Viewfinder view is you can drag the area on the viewfinder to define where to search. The area you drag will be concerted to the elevation angle (or altitude) and the azimuth. The altitude is fixed but the azimuth is a range. You can also drag the corresponding icon on the side to fine tune the values. The contour of the Half Dome really helps to determine the Moon location.

With just a few drags and clicks, I got the following three dates back. As you can see, only the last one meets all the conditions (winter, after 3pm).


Believe it or not, we just dated the famous photo. It was taken on December 28, 1960 around 4pm. The Moon is an 86.1% Waxing Gibbous. It would take hours of calculations but with this app, it is just a few minutes.

Since now I knew the moon position on the original photo, it is really easy for this app find all the date/time that match closely to the original photo. I just need to change the date range!

I googled a little bit and found in 11/28/2009, they predicted the Moon at the almost exact same location. They called it Moon and Half Dome Celestial Encore. You can find a link below.



Here is what this app shows on 11/28/2009. Unfortunately, no photo came out from that encore because there was cloud.

Of course, everyone would be more interested in when the next time would be in the future. So I set the starting date as today and the ending date to be five years later. Here is what I got for the next five years.


The best matching one is 12/29/2017. Sun and Moon position, time of the day are almost exactly the same as Ansel Adams’s Moon and Half Dome. If you would like to replicate the classic, that’s the time you should be at Yosemite.

Here is a quick comparison of 1960, 2009 and 2017. As you can see, the 2017 one is actually more accurate than the 2009 one in all aspects.

Date Time Moon Percentage Moon Azimuth Moon Altitude
(Original Photo)
16:05 86.1% 89.0 21.8
(Celestial Encore)
15:54 88.7% 88.7 21.8
16:06 86.3% 88.8 21.8



There is a full moon eclipse coming soon. You can find the exact date and time at http://www.timeanddate.com/eclipse/lunar/2014-april-15. Since I am in California, the actual starting time would be Apr 14 at 9:55 PM and Apr 15 at 3:36 AM. I really want to pre-visualize the whole process using the PlanIt! beta release which is the next release of the original PFT app.

Based on the calculation of PlanIt!, the moon starts at azimuth: 130°, elevation: 27° and ends at azimuth: 225°, elevation: 30°. Basically, from the southeast to the southwest for almost 95° rotation. If you want to use one lens to cover the whole process without using a motion control device, you need at least 16mm on a full frame camera which has a horizontal angle of view of 96.7°. If you have a 14mm, use it as 16mm will be almost from edge to edge.

Sounds simple but it is hard to visualize the numbers. Viewfinder is here to help. Please check out the video below where I simulate the whole moon eclipse using the time-lapse feature in PlanIt!.

In this video, I used the Half Dome as the background. I set the camera location at a location at the Snow Creek Trail. At this location, the Half Dome will be on the south.

The camera location (click for a larger image):


Moon position when eclipse starts:

device-2014-04-13-100808  device-2014-04-13-102315

Moon position when eclipse ends:

device-2014-04-13-100834  device-2014-04-13-102331

If you happen to be at Yosemite National Park, you can give it a try. Plan to camp at the Snow Creek Trail 🙂

If you are in other area of the world, you can find some other local landmarks to use it as the foreground of the whole moon eclipse – skyline, mountain peaks, lakes etc. The PlanIt! will definitely help you  to plan the shots accordingly. You could make a time-lapse of it. Or you can merge the photos at every 10 minutes or so using lightening mask into one photo.

Have fun!

We are working hard for our next release of the Photographer’s Field Tools. We decided to rename it to PlanIt! because we will introduce several apps in this Photographer’s Tools Series. The PlanIt! is the first app in this series. We have three more apps in the pipe line.

We also have a Google+ beta tester community opened. If you are existing Photographer’s Field Tools users who purchased the Pro version or purchased the in-app purchase of the Ephemeris features in the free version, we can invite you to join this community so that you get access to the beta releases.

You can find an updated tutorial which includes the new features.

PlanIt! Ephemeris Features (next release)

Here are a few screenshots of the new features. We called it the Viewfinder.

1. The view from the Glacier Point to the Half Dome. It is in a panorama. The Milky Way runs over the Half Dome at about 11pm and there is no moon. It will be a perfect night to capture the magnificent starry Glacier Point view.



The same view except the phone is rotated to landscape orientation so that you can see the viewfinder in a larger view.



2. To date the famous Ansel Adams’s Moon and Half Dome. You can find details in the attached pdf file. This screenshot below shows you another perfect date in 2017 that is almost the same as 12/28/1960 when Ansel took his legendary photo.



3. The time-lapse settings. Now you can set a different azimuth, elevation angle and focal length for the starting and ending times and we will visually show the whole time-lapse process to you in the viewfinder.


4. Simulate the star-trails. All the stars are at their real positions at the giving time.