Posts Tagged ‘geotagging’

Walking tour of CAHH parks

November 26, 2018

Hollin Hills is a development in Fairfax County, Virginia, about 10 miles outside of Washington, D.C. It has about 450 houses. It was designed by Charles Goodman and developed by Robert Davenport.” Source Credit: “Hollin Hills” website (no longer online).

The Civic Association of Hollin Hills (CAHH) owns and maintains seven small parks in the community: the Wildlife Sanctuary; Sutton Potter Park; Brickelmaier Park; Charles Goodman Park; Paul Spring Park; “Mac” McCalley Park; and Voigt Memorial Park.

All of the parks are located along streams except Sutton Potter Park and McCalley Park. The Wildlife Refuge/Sanctuary extends from Woodlawn Trail to the dogleg in the road at Boswell Avenue and Delafield Place. Two parks straddle creeks that are tributaries of Paul Spring, a stream that runs along Paul Spring Road: Brickelmaier Park runs from Popkins Lane to Paul Spring Road; Goodman Park runs from Marthas Road to Paul Spring Road. Paul Spring Park runs along Paul Spring from the intersection of Rebecca Drive and Paul Spring Road to the intersection of Rippon Road and Paul Spring Road, directly across the street from McCalley Park and Voigt Park. The upstream end of Paul Spring Park is near White Oaks Park, a mid-size park maintained by Fairfax County Park Authority.

Sutton Potter Park was featured in an article that appeared in Washingtonian Magazine, “Best of 2004: Sledding Hills.” I shot two photos from a viewpoint about halfway up the long hill: one looking downhill; another looking uphill. Trust me, neither photo provides a sense of the true steepness of the hillslope — a sled ride downhill could be either extremely exhilarating or very terrifying! The park entrance is located at the 7400 block of Range Road; another entrance is located behind the townhouses along Windbreak Drive.

The Wildlife Sanctuary is (or was) a good place to look for Mocha Emerald dragonflies (Somatochlora linearis). Peak activity was observed during July. A segment of Paul Spring, a stream located in Paul Spring Park, is (or was) good for Needham’s Skimmer dragonflies (Libellula needhami); the entire length of the stream is good for damselflies, including Ebony Jewelwing (Calopteryx maculata) and Variable Dancer (Argia fumipennis)/Violet Dancer (Argia fumipennis violacea).

The Backstory

During Fall 2010, I used my Apple iPhone 3G and an app called “EveryTrail” to create an interactive map showing the location of the entrances to the CAHH parks. At some point, I noticed the hyperlink to the interactive map stopped working.

As it turns out, ownership of “EveryTrail” transferred to “TripAdvisor” in 2011; EveryTrail was acquired by “AllTrails” in 2016.

All of the interactive trail maps that I created eight years ago survived two ownership transfers, much to my surprise! Some of the interactivity of the original maps was lost in translation, but hey, all is not lost. “Walking Tour of CAHH Parks” is the current iteration of the interactive map, available from AllTrails. See also “Walking Tour of Huntley Meadows Park (Ver. 2).”

Tech Tips

The “EveryTrail” app was used to record a GPX file that traces the route I walked.

Photos were shot at selected waypoints. All photos featured in both interactive trail maps were taken using the built-in camera of my Apple iPhone 3G; the photos were geotagged automatically by the iPhone’s GPS receiver.

Lost & Found: Another Alexandria, VA USA sundial

January 17, 2012

The North American Sundial Society Sundial Registry listing for Virginia Alexandria Dial #253 says, “May have been removed; could not be located 8/2005. Contacted historical society 12/2008 to confirm placement but no reply.” I’m happy to report the sundial is in fact right where it’s supposed to be! Well, sort of. The Sundial Registry lists the location of Dial #253 as, “NW corner of King & Cameron St.” That is, in a word, impossible: Cameron- and King Streets are parallel streets, as shown by a zoomed-in map of Old Town Alexandria. The actual location of the vertical sundial is the corner of Cameron- and N. Washington Streets, as shown by a geotagged full-size version of the photo and verified by the following screen captures from Google Maps Street View: facing east along Cameron Street toward N. Washington Street; corner of Cameron- and N. Washington Streets; facing west along Cameron Street toward N. Columbus Street.

Alexandria Dial #254 is a horizontal sundial located at historic Christ Church on the opposite side of Cameron Street from Dial #253. The Sundial Registry listing for Dial #254 says, “Horizontal circular bronze dial appears to have been designed for 32 degrees N.” Read more about this issue in my last post, “Sundial at Christ Church, Alexandria, VA USA.”

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Picasa Web Album: Alexandria, VA Sundials

Tech Tips: All photos in the preceding slideshow were geotagged automatically by an Apple iPhone 4. Apple Computer does not support Adobe Flash on its mobile devices, so embedded slideshows from Picasa Web Albums (such as the one shown above) will not display properly on the iPod touch, iPhone, and iPad. For this reason, you may need to follow the hyperlink to the photo album, then click on the slideshow icon (shown upper-right corner). Learn more about Google Maps Street View. Locate the sundials using the following search string in Google Maps: “Christ Church Alexandria”

Sundial at Christ Church, Alexandria, VA USA

January 15, 2012

A horizontal sundial is located on the grounds of historic Christ Church in Old Town Alexandria, Virginia USA. The North American Sundial Society Dial Registry listing says, the “dial appears to have been designed for 32 degrees N.” In order to determine whether the sundial is in fact aligned properly, I examined a couple of photos that were geotagged by my Apple iPhone 4. (See “Tech Tips” for details, below.)

Similar to setting the correct time on an analog clock or wristwatch (by moving the hands of the timepiece into proper position), properly orienting a horizontal sundial will move the shadow of the gnomon (or style) into position so that the dial face displays the correct time.

  1. The dial plate should be horizontal.
  2. The shadow-casting edge of the gnomon should be parallel to the Earth’s axis, inclined at an angle equal to the latitude of the sundial.
  3. The tip of the gnomon should point toward the North Celestial Pole (i.e., Polaris, the North Star). More simply, the dial face should be aligned so that 12 noon points toward geographic north and the 12 noon hour line is aligned with your local meridian.

Photos 1-2 of 8 (shown below) verify that the dial plate is horizontal. Photos 3-4 show the gnomon is inclined at an angle of 31.86 degrees (~32 degrees); Photos 5-6 show the latitude of the sundial is 38 degrees 48 minutes 22.2 seconds. Photos 7-8 show the image direction is 218.4602 degrees, meaning the tip of the gnomon is pointing southwest rather than true geographic north (0, 360 degrees).


Bottom line: The Christ Church sundial appears to have been made for another location and is aligned improperly for its new location. In other words, the sundial is strictly ornamental and will not tell time correctly.

Tech Tips: The iPhone Camera app works seamlessly with two built-in devices to geotag photos: the GPS sensor measures position on Earth; the digital compass measures “image direction.” PixelStick, an application for Mac OS X, was used to measure angles in one of the photos (see Photos 1-4, above). Apple “Preview” was used to display GPS info for both photos (see Photos 5-8, above).

Photos © Copyright 2012 Walter Sanford. All rights reserved.

Monarch butterflies on Butterfly Bush (white)

October 16, 2011

During a photowalk through Milway Meadows, a residential community in Fairfax County, Virginia USA, I spotted several Monarch butterflies (Danaus plexippus) feeding on the white flowers of a Butterfly Bush (Buddleja sp.). I have never seen so many Monarchs in one location — I estimate anywhere from six- to 10 butterflies were feeding on the same bush! I wonder whether the butterflies I saw were part of a larger group migrating south for the winter.


The preceding gallery features copies of the original photos (shown below) that were cropped and adjusted using Apple Aperture. Photos 11 and 12 were annotated using Apple Preview in order to highlight one or more butterflies that you may have overlooked. The photos in both galleries appear in the same sequence.


Tech Tips: The gallery (shown above) features some of the better photos from a batch I shot using my Apple iPhone 3GS after cell phone service was de-activated. (I just upgraded to an iPhone 4.) I was curious to know whether the de-activated 3GS would still geotag photos taken using its built-in camera. As it turns out, the de-activated iPhone 3GS (essentially the same as an iPod touch) did in fact geotag all of my photos. The accuracy wasn’t as good as usual (for details, see “The ABCs of A-GPS“), except in the case of the photos I shot while standing in the same place for a long time — I guess the phone’s GPS chip was able to get a better position fix when I was stationary for a while. I used Apple “Aperture,” a professional-grade tool for organizing and adjusting photos, to geolocate all of the photos correctly during post-processing.

AutoStitch Panorama app — new and improved!

October 14, 2011

With the recent release of AutoStitch Panorama Version 4.0 ($1.99), the best mobile panorama photo app just got better! Among several new features, the one that is most appealing to me is panorama photos now include geolocation data in the EXIF/IPTC info.

In order to test the new geotagging feature, I re-stitched a 21-image panorama photo of a field of Jewelweed (Impatiens capensis) spotted during a photowalk through the “Wildlife Sanctuary,” one of seven small parks owned and maintained by the Community Association of Hollin Hills, Fairfax County, Virginia USA; the resulting composite images are shown in the following gallery. Photo 1 of 2 is a cropped version of the composite image; Photo 2 of 2 is the “raw” composite image. Image 3 shows the FxIF Data (see “Related Resources,” shown below) that verifies the re-stitched composite images are in fact geotagged; Photos 4 and 5 show two views of the FxIF Data Map Link.


The following gallery shows the original composite images that were not geotagged by the older version of AutoStitch Panorama. Photo 1 of 2 is a cropped version of the composite image; Photo 2 of 2 is the “raw” composite image. Image 3 shows the FxIF Data (see “Related Resources,” shown below).


Related Resources:

  • Panorama photo app showdown: Field of Jewelweed (one of my recent Posterous posts)
  • FxIF is an add-on for the Mozilla Firefox Web browser that allows the user to view EXIF info — including GPS info, when available — by simply right-clicking on a Web page photo and selecting “FxIF Data.” The user may set preferences for coordinates (e.g., decimal degrees) and map display (e.g., Google Maps); for details, see the section entitled, “Configure me” on the FxIF Web page.

Panorama photo app showdown: Field of Jewelweed

September 30, 2011

The following gallery shows a 21-image panorama photo of a field of Jewelweed (Impatiens capensis) spotted during a photowalk through the “Wildlife Sanctuary,” one of seven small parks owned and maintained by the Community Association of Hollin Hills, Fairfax County, Virginia USA. The plant covered a broad area in a clearing of a deciduous forest, between two forks of an intermittent stream running through the park. AutoStitch Panorama app  ($2.99) was used to create the photograph: Photo 1 of 2 is a cropped version of the composite image; Photo 2 of 2 is the “raw” composite image.


I used 360 Panorama app ($1.99) to shoot a geotagged panorama photo of the same field of Jewelweed. A hyperlink to an online interactive version of the panorama photo is listed following the “flattened” version, shown below.


360 Panorama photo (interactive version)

Compare and contrast the AutoStitch Panorama composite image with the same shot created using 360 Panorama and I think you’ll agree with me that AutoStitch is still King of the Hill in the field of panorama photo apps.

Holes in Blue Atlas Cedar tree trunk

September 12, 2011


Holes drilled by sapsucker birds (Sphyrapicus sp.) in the trunk of a Blue Atlas Cedar tree (Cedrus atlantica). Photo 1 of 3 was annotated to highlight one of several rows of drill holes; Photo 2 of 3 is the original photograph. Habitat: Landscape planting in a residential community, Fairfax County, Virginia USA.

Tech Tips: The geotagged photos in the preceding gallery were taken using an Apple iPhone 3GS; Apple “Preview” was used to annotate Photo 1 of 3. The photos in the following gallery were taken using a Kodak M1093-IS point-and-shoot digital camera; Apple “iPhoto” was used to geotag the photos.


Rockies versus Nationals

August 23, 2011


My first visit to Nationals Park, Washington, D.C. USA, to see the Colorado Rockies (blue) versus the Washington Nationals (red) on 09 July 2011. The preceding geotagged snapshot shows the view from our seats in the stadium upper deck, first base side. Sincere thanks to my good friend Phil Wherry for treating me to good seats and a good time at the ballpark!

Project Noah versus Leafsnap

June 4, 2011

Project Noah and Leafsnap: Two free apps that utilize iPhone’s built-in camera for exploring the natural world; two different solutions for field identification of fauna and flora. One app works amazingly well; the other app works, but not as well. A list of pluses and minuses for both apps follows, along with a summary of the results of my field testing and a recommendation for educators.


Project Noah

(+) Visually appealing user interface (UI) – In a word, yes. [Image 2 of 12]
(+) Built-in camera – My Noah/New Spotting/”Take new photo” (plus access to iPhone “Camera Roll”) [Images 3 and 4 of 12]
(-) Built-in field guide – The Project Noah Field Guide is not a field guide in the traditional sense of the word, rather it is more like a crowdsourced field guide. Photos and related narrative text are submitted by Project Noah “citizen scientists”: Nomenclature and content quality varies widely throughout the field guide; some groups of animals and plants are either underrepresented or not represented. [Image 5 of 12]
(-) Feedback – “Help me ID this species.” I tapped “YES”; no feedback (since 23 May 2011). [Image 6 of 12] [Editor’s Note: Images 7, 8, and 9 of 12]
(+/-) Geo-referenced data – Optional map view available (see example); photos saved to “Camera Roll” are not geotagged (see example). [Images 10 and 11 of 12]
(+/-) Option to participate in actual scientific research projects – “My Missions.” Your field observations may never be used by real scientists unless you opt to participate in one or more missions. [Image 2 of 13]
(+) Performance incentives – “My Patches,” like virtual scouting merit badges [Image 12 of 12]
(-/+) Built-in documentation and Web support – No built-in help; better Web pages than Leafsnap.
(-) Universal app/iPad version – Not available



(+/-) Visually appealing user interface – Yes. Leafsnap UI somewhat less appealing than Project Noah. [Image 2 of 12]
(+) Built-in camera – “Snap It!” (plus access to iPhone “Camera Roll”) [Image 3 of 12]
(+) Built-in field guide – Database currently features 2,620 high-resolution images of 185 tree and plant species. [Image 4 of 12]
(+) Feedback – Immediate and very reliable. Leafsnap correctly identified 8/9 trees that I tested; the second result was the correct ID for the 9th tree (a fact verified easily by comparison with field guide database). [Image 5 of 12]
(+) Option to participate in actual scientific research projects – By design, all field observations are used to build scientific database.
(+/-) Geo-referenced data – Optional map view available (see example); photos saved to “Camera Roll” are not geotagged (see example). [Images 6 and 7 of 12]
(+) Performance incentives – “Geodialist’s Collection” (“Geodialist” is my Leafsnap username) [Image 8 of 12]
(+/-) Built-in documentation and Web support – Tap “i” on any page for more information; poor Web support. [Images 9, 10, and 11 of 12]
(+) Universal app/iPad version – iPad version available (“Snap It!” doesn’t work with iPad 1.) [Image 12 of 12]


Overall, Project Noah has twice as many minuses as Leafsnap, and there are more pluses than minuses for Leafsnap. Most importantly, Leafsnap provides timely, reliable feedback while Project Noah fails to deliver this key success factor consistently.

As a former science teacher, I am conflicted by the thought of using Project Noah with students. I’m a big advocate of hands-on learning (a.k.a., learning by doing) and technology-enriched instruction. But I prefer “guided discovery” over random experimentation, that is, carefully crafted hands-on activities designed to lead students to scientifically accurate conclusions. At best — that is, with guidance from a good teacher — working with Project Noah could be a great experience for students; at worst, it could be an exercise in frustration (see Editor’s Note, shown below). Bottom line: Leafsnap is the only app I recommend for use with students. In my opinion, Project Noah is more appropriate for adults than children.

See the related blog post, Field test: Leafsnap app.

Editor’s Note: In the interest of fairly evaluating Project Noah, I re-tested the app by adding a “New Spotting” to “My Noah.” I tapped “YES” in response to the prompt, “Help me ID this species.” This time, I received two “Comments” later the same day, as indicated by the red badge on the “My Noah” page. I tapped “My Spottings”: On the “My Spottings” page, I tapped the right arrow on the first “Needs ID” spotting (that displays an icon indicating two comments); on the “Comments” page, two Project Noah participants correctly identified the plant as a Hydrangea macrophylla (Lacecap). Sounds good — that’s the way it’s supposed to work, right? A couple of questions arise: 1) What are the qualifications of the commenters? (With no disrespect intended, aren’t you naturally a little skeptical of someone who goes by the moniker, “Monkey-mind?”) There is no way to either access a commenter’s bio, or communicate directly with a commenter via Project Noah unless the commenter enabled these options in their settings. 2) What if the commenters had misidentified the plant? Not so good, and arguably worse than no feedback. (Remember the teachers’ old saw that says students must work harder/longer to unlearn misconceptions and misinformation? It’s true!) Project Noah’s highest priority should be to devise a procedure that provides timely, reliable feedback EVERY TIME a participant requests help; until this objective is achieved, I remain very reluctant to recommend its use by educators.

My Top 30 iPhone Photos — A One-Year Retrospective

May 26, 2011

I bought a used Apple iPhone 3G a little more than a year ago; I upgraded to a used iPhone 3GS a few months later. iPhoneography rekindled my interest in photography. I have taken more than 1,500 photos using my iPhones during the past year — that’s more photos than I’ve taken in years! Inspired by a recent Tweet from professional photographer Rick Sammon

Selecting your best photos can be challenging — as well as quite rewarding.

… I started a project to select my best iPhone photos from the past year. Along the way I learned about some of the advanced features of Aperture, a professional-grade tool for organizing and adjusting photos. Embedded in the EXIF/IPTC info of every photo is a title, caption, one or more keywords, copyright notice, and a geotag.

Conventional wisdom says I should rank the photos and lead with my best shot; I chose to present the photos in chronological order instead. In this order, the gallery reflects the passing of time as well as the persistence of my interests. Here they are — 25 of my favorite photos, and five of my favorite panorama photos. All photos were taken using the iPhone’s built in camera; photo 16 of 25 was post-processed using Diptic app.


Panorama photos 1 through 3 (shown below) were created using AutoStitch Panorama app; panorama photos 4 and 5 were created using Photosynth app (panorama photo 4 was adjusted and cropped using Aperture).


Tech Tips: You may be wondering, “Why did you buy used iPhones?” If you have a used smartphone, then you do not have to commit to a long-term contract with a wireless phone service provider. That’s a gold nugget of wisdom I’m happy to share! “FxIF” is an add-on for the Mozilla Firefox Web browser that allows the user to view EXIF info — including GPS info, when available — by simply right-clicking on a Web page photo and selecting “EXIF Data.”

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