Points & Pixels

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Creating Stockpile Footprints in Topolyst
Several months ago, I introduced Topolyst, our small Unmanned Aerial Systems (sUAS) processing software. One of the great features in Topolyst are tools to automatically create the footprint ("toe") of a stockpile and to optionally classify overhead points so that they are excluded from subsequent processing (such as cross sections or volumetric computations). An example of a stockpile with an overhead conveyor, prior to toe finding and classification, is shown in Figure 1. As seen in the 3D view in the upper right, the conveyor simply blends in with the stockpile, giving a grossly inaccurate volume for this pile.

The data following Topolyst’s automatic stockpile extraction are shown in Figure 2. Note the toe in the Map and 3D views as well as the automatic classification of the portion of the conveyor within the toe. This is an extremely powerful tool available in Topolyst (or in LP360 Advanced) that reduces the work of collecting stockpile volumes significantly. Our initial release of Topolyst also includes a very powerful collection of 3D feature editing tools that make quick work of manually digitizing toes or cleaning up toes in difficult locations (for example, along pit walls) following automatic extraction.

We have found, from completing many stockpile surveys, that correctly defining the toe is just the beginning! Mine site operators are keenly interested in consistency. For example, suppose a stockpile is measured on 5 January to have a volume of 1,000 yards3. The plant manager sells 500 yards3 from this pile during the period up to the next survey. She also estimates that 1,000 yards3 were added to the pile. The next survey should indicate a volume close to 1,500 yards3. If it does not, the person measuring the volume is the first suspect!

What are the causes of these discrepancies? The first is, of course, poor estimation. It is much more difficult to accuraely estimate the volume of a pile by "eyeball" than one might guess. However, we have found the primary culprit to be the definition of the base of the stockpile.

Many mine sites keep a priori survey data that represent the terrain prior to placing any stockpiles ("baseline data" or simply baselines). Nearly all of the baseline data provided to us has been stereographically collected from a manned aerial survey. An example is shown in Figure 3. The magenta points are 3D "mass points" that were derived from a conventional photogrammetric stereo model.

The question arises as to how to consistently employ these baselines? There several approaches that one can take:
Get the mine site owner to agree to use the true surface at the time of data collection and abandon the use of "baseline" data. There is a lot of argument for this since it is seldom that the subsurface material will be used. However, a big one time inventory adjustment may have to be made.
Use the 3D toes to define the vertical edge of a stockpile but pull down the base geometry using the baseline data
Generate a surface model from the baseline data and then use the toes to only define the planimetric placement of the stockpile.

The third method probably gives the most consistent change of volume record from survey to survey but is it the most technically correct? This method assumes that all of the material from the toe to the baseline (recall that the baseline is actually under the surface on which the toe lies) could be extracted and used/sold. This is usually not the case.

As mappers of data, it is important that we advise mine site operators of the advantages and disadvantages of the various methods but, at the end of the day, produce the data according to the customer’s instructions.

Topolyst supports all of the aforementioned techniques for computing volumes (as well as a few others). For example, the hillshade of Figure 4 is a surface model constructed solely from photogrammetric mass points. Topolyst has the ability to dynamically use these data as the base where computing volumetrics. Topolyst also has the ability to generate a LAS file from point, polyline and polygon feature data. This is extremely useful since this "baseline" LAS can be used in a wide variety of analysis scenarios.

The features we are adding to Topolyst are being driven by our customer needs, our own needs within our analytic services group and by our research and development efforts aimed at process improvement. I very definitely welcome your feedback on current and needed features in this great product.

For more information, visit: www.airgon.com

TopoFlight Mission Planner
TopoFlight Systems, Switzerland has released the TopoFlight Mission Planner, version 10. The Flight Planning Tool calculates the exact number of lines and images needed for a pre-defined area. The program is designed to provide flight plans for virtually any camera or sensor, deducing cost quotes out of flight plans, eliminating waste and maximizing efficiencies while concentrating on accuracy and quality control. In this release the main focus is set on LiDAR flight planning to assist the user to get and visualize the required point density, MTA zones, coverage, etc. TopoFlight is now used in over 23 countries. The following list shows some of the most important improvements:
Terrain following flight planning and execution
Improved and extended import / export functions
New developments and advancements for LiDAR flight planning
TopoFlight Mission Planning is now 100% RIEGL compatible

TopoFlight Systems also made several improvements in the Flight Management System, the TopoFlight "Navigator". Navigator can now lead the helicopter pilot in "terrain following missions". The current version is 5.0.

TopoFlight is the most efficient 3D flight planning software for interactively planning your aerial survey missions. TopoFlight `Navigator’ Flight Management Software offers a highly flexible way of integrating and controlling your airborne sensors.

The Flightplanning Tool is used by small and large private mapping companies and flight services and at many different government agencies and militaries.

Further experience of the Support team:
Custom Programming for User’s requirements
Flight planning of photogrammetric and LIDAR flights
Flight operator
Post processing GPS/IMU data from aerial flights
Processing images with various SW programs
Aerial triangulation
Advanced image processing

TopoFlight training is available in English, Spanish, French and German, etc.

For more information, visit: www.TopoFlight.com and www.nts-info.com TopoFlight Systems, Developer of TopoFlight Gemeindemattenstrasse 4 CH-3860 Meiringen, Switzerland Tel.: +41-33-972-3030 e-mail: klaus@topoflight.com New Tech Services, Inc. Worldwide Marketing P.O. Box 16301 Sugar Land, TX 77496-6301, USA Tel: 1-281-573-8029 e-mail: info@TopoFlight.com

Laser Scanning is the Easy Part
With laser scanning becoming the norm, I continue to see examples of projects showing a point cloud of this and a point cloud of that. While awesome, personally I prefer to see the end product, show me the deliverable please. (Yes, I know sometimes the point cloud is the deliverable.)

In a majority of projects, the physical laser scanning is the easiest part of the project. What you do with the data is what the client is paying for. A question to ask yourself is "How do I satisfy the contract and give the warm and fuzzies to the client?" The majority of the time a pdf is asked for by the client, that my friends is the hard part. Non-technical users want to see the product they are paying for. Place a point cloud in their hand and eyes will roll.

Below is an example of a project where a new building is being squeezed in between two existing buildings. The critical aspect is how the existing buildings relate to the property lines.

The scan itself was performed with a Leica Nova MS60 Multi Station. Utilizing Leica Cyclone the data was imported, the property lines were projected in the Z direction as a plane, and a color Deviation Map was created to show the distances from the property lines to the faade in a graphical manner.

Expanding on the deviation maps, sections were cut in the xy plane to dimension the building faade at specified elevations to the property lines. AutoCAD was used to wrap up the deliverable in a presentable manner and globally usable manner.

Written by Shaun Lewis, James G. Davis Construction,ww.davisconstruction.com

3D Scanning Helps with the Restoration of a World War II-Era Shipyard Crane
Our world of 3D scanning continues to take us to amazingly interesting places to scan amazingly interesting things. Often our interest alone drives us to go out and scan. This project is no different.

In the fall of 2015 we learned about such an interesting historic object, an icon that overlooks the Baltimore city skyline that needs a serious restoration. A relic from the once bustling World War II-era shipyards, this gigantic crane was standing on its last leg. Its current owner, the Baltimore Museum of Industry, had just started a capital campaign to restore the crane to its former glory.

So of course, 3D scanning can help (it always helps, right?), although initially we actually weren’t sure how, but we just had to go down and scan this baby and figured we would determine later how the 3D information would contribute to the effort.

On a crisp fall day we stopped over at the museum, pulled out our FARO Focus3D X 330 and took about a dozen scans from various vantage points on the ground and also on the museum rooftop. In all we spent maybe 2 hours on site including the mini-tour we took through the museum to get on the roof.

We then set out to process the scan data starting initially with data registration. Having not bothered with targets, we processed in Innovmetric’s PolyWorks to accurately best-fit the data sets to each other. Another few hours into the project.

Now the real fun began. As many of us know, scanning is the easy part. But very often, at least for us, delivering a raw or even cleaned up point cloud is not very meaningful to end users. In this case the end users could be just about anybody involved in an historical restoration project for a large steel crane: structural engineers, scaffold designers, paint experts, lighting designers, even giant U.S. flag consultants and a laser light projection team.

One more use for this crane data not originally considered is for the creation of collectibles and gifts based on this unique 3D data. Using digital fabrication methods, such as 3D printing and laser etching, awards, gifts, even jewelry can be created based directly on the 3D data from the scans. Given the local appreciation for this icon, these can become quite treasured collectibles to a lot of people, and helpful to the fund raising effort.

In order to prepare the data for all of these use cases, we undertook the effort to `reverse engineer’ the raw scan data into true 3D CAD geometry. This means creating each and every structural beam, cross member, and plate as accurately as we can from the point cloud. We did this using various CAD software including PolyWorks, Geomagic, Rhino3D, and Autodesk Revit & Studio.

Clearly this entire process was a labor of love based on our appreciation for 3D scanning and modeling technologies for helping with real problems. We’ve contributed toward many other pro bono projects of this same nature where we can demonstrate the power and capability based on 3D scanning. I hope we can continue to help with projects like this.

See The Sun Papers for information and pictures of the crane at the Baltimore Museum of Industry.

Michael Raphael Founder and CEO Direct Dimensions, Inc. June 2016

AAM Group Urban Modelling to Support Smart City initiatives
Client name: Hong Kong Special Administrative Region
Location: Hong King, China.
Description of the data: Oblique Imagery, and LiDAR
Resolution: 10cm GSD (nadir) oblique imagery
Points per sqm: 4 pt/m2 at 3cm rms vertical accuracy

Hong Kong’s "Smart City" concept was first raised in 2008. It has been labelled a priority for the Region, with the concept getting special mention in the 2015 and 2016 policy addresses.

AAM began this process with Hong Kong in 2011 when authorities required a Territory-wide terrain and surface definition for planning and geotechnical applications. To this, was added a pilot 3D digital city model of the Central / Wan Chai area. The urban city model required spatial accuracy to support engineering and scientific calculations which would endure legal scrutiny. Photorealism was added to this geometric rigour to engage public consultation and to provide an identifiable backdrop to complex planning scenarios.

AAM’s K2Vi software package was added to visualise and analyse the wide range of spatial data types available in the 3D urban model: terrain, orthoimagery, textured building models, LiDAR pointclouds, vectors, attributes and animations.

Urban Hong Kong is an extremely complex environment, where space is a scarce resource, and detailed 3D planning is needed to assure the space is used wisely and in a sustainable way. Everyone needs to find smarter ways of doing things. City planning depends on the analysis of the current situation and assessing the impact of proposed changes. The analysis can be done in 2D, but if there is anywhere in the world where the third dimension is vital, it is Hong Kong.

AAM began performing aerial surveys over 50 years ago, using film cameras and slide rules. Today we have GPS-equipped planes, UAVs, digital cameras, lasers and powerful computers, allowing us to perform rapid surveys over large areas with high accuracy and turnaround.

For more information contact David Jonas at d.jonas@aamgroup.com

A 6.623Mb PDF of this article as it appeared in the magazine complete with images is available by clicking HERE