Orthomosaic Mapping and Photomapping, Part 2

This 40-acre cornfield is a composite of 326 images

This 40-acre cornfield is a composite of 326 photos

Part 1 focused on orthomosaic photogrammetry maps – our high-tech mapping service that delivers image files with embedded position and altitude information for each pixel. Another service that we provide – photomapping – uses a more familiar image processing technique known as photo stitched panorama.

Although the photo collecting technique is similar to orthomosaic mapping, position and altitude information are tossed in favor of the less complicated panorama image processing. We use professional software to align features in the overlap areas, stitch the images together, and shade the transition zones.

Panorama Software is Common, but How Does it Work?

Panorama software works best when the camera is fixed and all images are taken from the same point in space. However, when using a moving camera the altitude must be high and a large overlap used. Therefore, we use the same flight control software and settings for photomapping that we use for orthomosaic mapping.

Our photomaps have the same high resolution as orthomosaic maps, but avoid the expense of the mapping service for generating 3D map sets. If position and altitude information aren’t required, then this is a less expensive way to get ultra-high-resolution maps of large properties.

Map Image Resolution (Geek Alert!)

Our Phantom 4 Professional V2 drone takes images that are 5,742 pixels across and 3,648 pixels high, which yield an image size of 19.98 megabytes (rounded to 20 MB). At an altitude of 400 feet, that image represents a ground view that’s 600 by 400 feet. Dividing pixels by distance yields the spatial resolution, which in this case is 9.6 pixels per foot. (In metric units, that’s 3.2 cm/pixel.)

For example, take an acre of land, which is 43,560 square feet. When photographed at an altitude of 400 feet, one acre takes up 18% of the camera’s image. The area-to-image ratio is scalable, so an orthomosaic map or photomap of 40 acres can be covered with 8 images. The composite image size is then 145 megapixels (MP), with a resolution of 3.2 cm/pixel. The key word here is “composite,” since a large number of photos (e.g. 326 photos at 20 MB each) contribute to this composite image.

Since a map’s image size is proportional to the number of acres, we can estimate your finished map’s image file at 6 MP per acre. This number can grow 20% or more because we’ll always be photographing a larger tract than required. In terms of file size, the finished JPG image file will end up at about 3 MB per acre.

Want to Proceed? Here’s What We Need to Know:

When specifying a mapping job, clients just need to provide their tract boundaries and we’ll take care of the rest. We’ll determine the appropriate parameters, such as 85% overlap frame to frame, 85% overlap track to track, and flying altitude. Overlap is partly determined by the height of objects on the ground (such as trees) and seasonal variations (such as leaves).

Our flight control software will use this information to generate the photo-taking commands to be used by the drone’s autopilot, which ensures the photo-taking process is accurate and repeatable. This is especially useful if the map needs to be updated for project progress or for seasonal variations.

Viewing Large Image Files on Your Computer

For our example above, a 145 MP image is too large to display on common photo viewers such as the MS Office Picture manager. However, it can be viewed with more advanced software such as Adobe’s Photoshop. Of note, we can resize large images so they’re viewable on your photo viewer, but the resolution will have to be decreased.

How Much Will Map Services Cost?

Every job has its own unique requirements, so we don’t publish our prices. However, our prices are very competitive and we deliver an excellent value. We’re happy to take your map requirements and give you an estimate within 24 hours. We guarantee our work will meet or exceed your requirements.

Call or e-mail. We’d love to hear from you!

Orthomosaic Mapping and Photomapping, Part 1

Aerial Drone Photography is the Ideal Technology for Orthomosaic Mapping and Photomapping!

Digital Elevation Model

Digital Elevation Model Topographical Map

Realm of Possibilities

In this article, the term orthomosaic mapping is used to describe the orthomosaic photogrammetry mapping technique, which is a computationally-intense method that yields position and altitude information for each pixel in the map. The term photomapping is used to describe the use of photostitching software to generate large panoramic maps.

Our orthomosaic map deliverables include: ultra-high resolution 2D maps, 3D Digital Elevation Model (DEM) topographical maps, 3D models, and 3D point clouds.

Our Photomap deliverable is a 2D map image similar to Earth-type maps but with ultra-high resolution.

As implied, “high-resolution” means these map image files can be very large – on the order of 3-4 megapixels per acre. For example, an 80-acre map will have around 300 MP and a JPG image file of around 160 MB. Large files for sure, but the terrain detail is amazing!

Who Can Use Orthomosaic Maps?

Surveyors, Architects, and Civil Engineers are several of the many professions that use orthomosaic maps for their land development and construction projects. They have the budget for high-end software, which can further process our orthomosaic map products.

Real Estate marketers and landowners may also need high resolution maps but don’t want to make the significant investment in photogrammetry software. For these users, we offer photomaps, which provide beautiful full-color map images. More on photomapping in Part 2.

Either way, these maps have high enough resolution to detect very small features. For example, a 1 foot by 1 foot object is represented with around 100 pixels. Tract size can range from less than one acre to thousands of acres.

What Makes Aerial Drone Orthomosaic Maps So Special?

Three dimensional computing is at the heart of calculating position and altitude information for each pixel. The numerically-intense software that does this, to my knowledge, hasn’t been made available for personal computers, so most users have to use online mapping services. For more detailed information on how this specialized software works, please refer to this article at ScienceDirect.com.

How Is It Done?

Orthomosaic mapping software requires many photographs of the landscape so each pixel gets multiple look angles. The software then assigns position and altitude information to each pixel. As you might reason, this is a very complicated process. To get good results, very high overlaps of the subject area are required – on the order of 75 to 90%. This requires that each ground point is photographed 16 to 100 times.

Aerial drones with precise GPS-based navigation are ideal for photographing landscape with this kind of precision. Hundreds or even thousands of high-resolution photographs are taken, typically looking straight down, and stored on the drone’s internal memory card. Back at the office, these photos are then uploaded to the mapping service and reconstructed by their orthomosaic software to create stunning, full-color maps, DEM maps, 3D models, and point clouds.

To achieve good results, the drone’s altitude must be around 4-5 times the altitude of the highest object, such as trees. The algorithms work best when there’s low wind and lots of leaves on the trees. Water can be a challenge due to its reflectivity. With less-than-ideal photography, the algorithms have difficulty assigning position and altitude information to the pixels. If done incorrectly, the resulting map either has strangely-shaped areas or areas that are blanked out.

Orthomosaic Map Deliverable Products:

  • 2D Map – full-color image of the landscape, including position and altitude information.
  • Digital Elevation Model – color-coded for elevation, any color scheme is possible as well as contour lines.
  • 3D model – full color three dimensional image. The model can be viewed on-screen from any perspective.
  • Point Cloud – typically viewed with high-end software. It’s a full color 3D model using points.

In part 2, we’ll examine photomapping, which will be of particular interest to real estate marketers and landowners.

What Should I Expect To Pay For Aerial Drone Photography Services?

Let’s Start With Some of the Costs of Running a Business . . .

The Business Part of Aerial Drone Photography

The Business Aspect of Aerial Drone Photography

. . . specifically, our drone photography business. There are many operating costs spread across aerial photography operations. They include: drone hardware, accessories, digital camera, camera glide, desktop computer, laptop, tablet, software, office expenses, Internet access, desk phone, mobile phone, aviation liability insurance, FAA certification, transportation, accounting, banking, taxes, etc. These costs are spread across all of our services.

Is a Drone Shoot that Complicated?

We go through a lot of effort to deliver results so you don’t have to deal with these burdens. A hobbyist can go out and buy a drone for less than $500 and then go into “business.” However, that is where the similarity ends. A professional drone operation is so much more than that, so let me explain some of the preparations that go into every drone photography session:

  1. The first step is receiving the task from our client. Through phone conversations and e-mail, we learn about the location and type of photography services desired. (Photography in this article includes videography.)
  2. From there, we look up the location on Google Maps; then check against the FAA’s restricted flight zones. We can fly in certain areas, but others are off limits for drones. Please read our blog.
  3. We then hand-chart the flight requirements onto a hard copy from Google Maps. Tools include self-developed programs to calculate altitudes, speeds, camera tilt angles, fields of view, etc. We know how to translate the client’s requirements into drone commands and can visualize what the camera’s field of view will look like. We’re good at this, very good. Usually, we get our shots on the first try!
  4. Flight requirements are then entered into drone flight programs. We use several, and select the appropriate program for the mission. Some examples: videography, surveying, mapping, etc. Programmed drone flights provide smooth, repeatable missions. This is particularly useful if the client wants us to fly the same mission again, such as for progress reports or seasonal changes.
  5. Driving time to the client’s site is one of our major cost drivers. We need to charge for extra driving time outside our service area.
  6. On site, we look over the terrain for obstacles that may pose a hazard to our drone, such as trees, power lines, light poles, water towers, etc.
  7. The fun part, flying the drone, goes relatively quickly. The preparation steps above help to ensure a successful mission; while collecting the required photography takes less than 20 minutes.
  8. If the client is on site, we download the photography to their computer or give them their files on a USB thumb drive. Otherwise, we upload their files within 24 hours to a cloud service and send them a link. We operate a fee-for-service business, and deliver unlimited copyright with our products.
  9. Returning to the office, we download the files to a desktop computer and back them up onto a storage server. Periodically, we back up client files to BluRay disks and retain them for several years.
  10. Of course, collecting our fees, processing credit cards, accounting, paying taxes, sending receipts, logging flights, etc., all add to the time commitment.

Just a Quick Note on Postprocessing

If the client has asked for postprocessing services, we have a number of high-end desktop programs for photography, videography, and mapping. We’re experts with this software, taking the uncertainty out of the equation and delivering products that meet or exceed the client’s expectations. Examples of our postprocessing products can be found on our Portfolio page.

So, Just How Much Time Do You Spend on a Standard Drone Shoot?

Six hours, which typically breaks down into thirds: (1) Client communications; (2) Mission planning; and (3) Executing the mission. Compared to most other skilled trades, our prices are very reasonable. In the end, we’re in business to earn money, but it just comes down to the fact that we love to fly!

Zoom-in With a Fixed Lens Camera

Zooming In With Your Drone's Fixed Camera Lens

Zoom-in With Your Drone’s Fixed Camera Lens

At one time or another, everyone has had situations where zooming in on a video clip adds that finishing touch. Whether it’s for effect or for greater stand-off distance, the convenience of camera zoom takes your photography to the professional level.

In this blog, I’ll show you how to get Full High Definition (1080p) results at a zoom factor of 1.4x using a fixed-lens camera. This is good information for venues like sporting events and weddings, which can be recorded from the air but at a great enough distance so the drone’s presence has minimal notice. For more information on camera resolution please read my blog Setting Up Your Aerial Drone Camera.

Do I Need an Expensive High-End Drone and Camera?

Although that would be one way to get zoom capability, it can be a very expensive investment. But, let’s look at just one of many high-end drone/camera solutions:

For a modest investment of $5,000 you can purchase a DJI Inspire 2 drone, Zenmuse X5S camera, and Lumix 14-42mm zoom lens and the results will be quite professional. The Lumix lens gives you the standard camera focal length equivalent of 28-84mm. So, with 50mm as the standard for zero magnification, this camera has a zoom range of 0.6x wide angle to 1.7x telephoto. Remember these numbers.

Is There a Less Expensive Alternative?

There’s another solution that is far less expensive and provides excellent results. Many drones on the market can record Cinema 4K video, which has a resolution of 4096×2160 pixels. However, most users are satisfied with a Full HD resolution of 1920×1080 pixels.

What these numbers mean is that to get a digital zoom capability, you can record video in Cinema 4K mode, which leaves plenty of resolution to render any portion of the frame in Full HD. Rendering the video is done in post-processing, where video clips are transformed into the finished video.

For example, we can use our drone to record the desired scene in C4K mode. We start with the equivalent wide angle focal length of the camera’s lens, which is 35mm (0.7x). Using post-processing software, as much or as little of the C4K image can be cropped for the desired magnification. So, when your video is captured in C4K, you can select a crop “window” of up to 50% and render your new “zoomed-in” video in beautiful FHD. In other words, you get a full-definition 1920×1080 pixels! For this level of cropping, you achieve a zoom factor of 1.4x, equivalent to a 70mm telephoto lens.

Compared with the $5,000 solution, which zooms 0.6x to 1.7x, this digital zoom technique gets you 0.7x to 1.4x.

Any More Slick Ideas?

Two for sure . . .

  1. If you want even more zoom, just crop to get the desired magnification. There’s no limit to how much you can crop, though you will start to see the results of lower resolution. For example, you can crop at 25%, which gives you a zoom factor of 2.8x (140mm telephoto) but the resulting FHD video will display a lower resolution of 1024×540 pixels.
  2. Any method of zoom will increase the image’s sensitivity to camera movement. So a small and acceptable level of vibration at 0.7x may be objectionable at 1.4x. Unwanted vibration can be minimized in post-processing using image stabilization. For more information please read my blog Video Production and Post-Processing.

At FAD-Photo, we use the DJI Phantom 4 Professional V2, which provides a highly stable platform capable of stunning high definition photographs and videos. We have mastered the art of taking C4K videos and using our post-processing software to minimize vibration and render FHD videos.

We deliver the results you would expect from a professional aerial drone photography service! For more information, please refer to our Aerial Drone Photography and Video Services page.

Video Production Sound Track

Recording Your Voice Using A Cell Phone

Recording Your Voice Using A Cell Phone

I mentioned in last year’s blog on post-production processing that the sound track can be tricky. Especially when the client wants music that they’ve heard from other media sources (such as the radio, TV, concert, CD, etc.) These sources are almost always copyrighted and the owners can (and probably will) track down violators and demand compensation.

Beware, The Music Industry Has Their Ways!

Last year, I know someone who came up with a slick idea to digitize a 1960’s record album and used about 30 seconds of it on a YouTube video. YouTube recognized the song, identified the copyright holder, and gave them a warning! So, you can’t be too careful about copyright violation.

How Much Will It Cost For A Music Track?

The cost for a music track depends on the service. For example, TripleScoop licenses 3-5 minute music tracks for $60 to professional photographers (this is my class). However, for small businesses, such as real estate listings, their licenses run $120. Large businesses will cost even more.

I once had a client ask for a specific song and I had to track down the copyright owner. It happened to be a big Hollywood outfit, Universal Music Publishing Group. They quoted $1500 per month to play this track in a small business marketing video! Needless to say, this expense was not in the client’s budget.

In addition to the cost for acquiring a commercial music license, there’s also the time required for the post-production part of it. This can be significant and includes searching for suitable music, getting a quote for the license, getting the client’s approval, purchasing the license, and coordinating the audio track with the video. Sometimes, several iterations are required until the client approves the finished video.

Are there penalties if you get caught by the copyright owner? Yes, and they’re covered by U.S. federal law under Title 17 US Code Section 106. Damages can include fines and court expenses.

The Path of Least Resistance Often Works Best

The challenges above are among the reasons that a client’s voice track works so well. First, the client owns the copyright on their own voice recording. Also, it personalizes the video to their prospective clients.

How to Record Your Own Voice Track

Clients often take my draft video and practice their narrative with it. Then record their voice using a cell phone (e.g. using Voice Recorder/Voice Memo) and send me the .M4A (MPEG-4 Audio file). Such a choreographed voice track works well for my post-production work. When appropriate, I can add a 15 to30 second stock music snippet to the introduction and end.

You will find examples of sound tracks in the videos posted to my portfolio page.