mikeroyal/Photogrammetry-Guide

Photogrammetry Guide

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A guide covering Photogrammetry including the applications, libraries and tools that will make you a better and more efficient Photogrammetry development.

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Table of Contents

Getting Started with Photogrammetry

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Photogrammetry is the art and science of extracting 3D information from photographs. The process involves taking overlapping photographs of an object, structure, or space, and converting them into 2D or 3D digital models. Photogrammetry is often used by surveyors, architects, engineers, and contractors to create topographic maps, meshes, point clouds, or drawings based on the real-world.

Types of Photogrammetry

• Aerial photogrammetry is the process of utilizing aircraft to produce aerial photography that can be turned into a 3D model or mapped digitally. Now, it is possible to do the same work with a drone.

Image credit: Forestrypedia

• Terrestrial (Close-range) photogrammetry is when images are captured using a handheld camera or with a camera mounted to a tripod. The output of this method is not to create topographic maps, but rather to make 3D models of smaller objects.

Image credit: TLT Photography

• Stereo Photogrammetry is a process that involves the estimation of 3D coordinates of points on an object by considering the measurements made of two or more images taken from different positions. The sensor looks at angles that are horizontal or oblique to collect accurate, detailed information for primarily engineering purposes, such as mapping the infrastructure of bridges, buildings, and dams.

Image credit: Stereo Photogrammetry Capture. HELImetrex

Photogrammetry Techniques

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Cameras

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DJI Zenmuse P1 Full-frame 45MP camera.

Links to Helpful Resources:

General camera-type recommendations

Here are some categories in which you should start your research:

Camera Photogrammetry Nikon D300/5mm precision GPS setup for VORTEX2. Image credit: NOAA

Fully automatic operation:

• Default: high-end phone.

• Some more flexibility in a zoom range: high-end compact camera (as in the Sony RX100 line).

• More flexibility, including distant subjects: high-end superzoom camera (as in the Sony RX10 and Panasonic FZ1000 lines).

• Extremely distant subjects in daylight: consumer superzoom camera (as in the Nikon P line, Panasonic FZ80, etc.).

• Default: mirrorless camera.

• Cheaper alternative (no mirrorless camera that suits your needs is available under budget): DSLR.

  If you’re absolutely sure that’s the only lens you’ll need: fixed prime lens camera (as in the Fujifilm X100 and Ricoh GR lines), high-end compact camera or high-end superzoom camera.

Key concepts and terminology

There are some concepts, terms and features of a camera that you’ll need to learn about to really understand camera reviews and see how one camera differs from another. The following is a list of such terms for you to look up if needed.

Camera Basics. Image credit: Geodetic Systems, Inc

• Exposure, noise, dynamic range (SDR and HDR).

• Camera design: interchangeable-lens cameras and fixed-lens cameras, mirrorless and DSLR.

• Image sensor: size and surface area, resolution.

• Lens: focal length and angle/field of view, maximum aperture, lens mount and format coverage.

• Autofocus.

• Continuous/burst shooting, buffer depth.

• Viewfinder and display.

• Image stabilization.

• Weather resistance.

Remember a camera’s age is irrelevant. Cameras don’t age like smart phones or computers do, because they have no increasingly demanding software to keep up with. So as long as a camera is in good working order, it should work as well as it did when it was brand new.

Make sure to shop at well accepted and well established in the camera market, even at the high end. Try reputable outlets (KEH and mpb) and the used sections on big retailers (B&H and Adorama in the US) and local camera stores. You can also find refurbished cameras sold directly by the manufacturers’ distributors.

Drones

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Links for Drone photography:

A drone is basically an Unmanned Aerial Vehicle (UAV). Before the rise in consumer interest in UAVs, the word “drone” was primarily used to refer to the UAVs used by the military.

Now, though, intelligent quadcopters that have UAV-like features are more popular among consumers than ever before. And while they technically aren’t as advanced as military drones, we refer to them as ”drones” because they are similar in nature (both allow you to operate an aerial vehicle in order to perform a particular task, which, in the case of consumer drones, is typically to shoot video or capture still images).

There are different types of drones for all kinds of situations, so make sure to consider the main purpose for your drone purchase. Even though most drones fall under the categories of consumer or professional grade drones, there are now UAVs geared towards traveling and selfies.

• Camera drones: These drones might range from $100 to $1000 which have exceptional features that make such drones a market leader in the world of professional drones. They also have Obstacle avoidable sensors.

• Compact drones: These drones are specially designed for panoramic images and landscape shoot. The best feature of compact drones is that they have an ability to change the image format from JEPG to raw images. Raw images have more details and can produce 4k quality of the picture and videos. For example, DJI Inspire 2, which falls in the category of professional drones has a speed of 60+ miles per hour (97+ kilometers per hour) and has a dual battery backup of up to 30 minutes. Use these drones in the places where you cannot step in and take the pictures that you don’t need to crop or it can adversely affect the quality of the picture.

The different among RTF, BNF and ARF:

• RTF stands for Ready-To-Fly - Usually an RTF quadcopter doesn’t require any assembly or setup, but you may have to do some simple things like charge up the battery, install the propellers or bind the controller to the quadcopter (get them talking to each other).

• BNF stands for Bind-And-Fly - A BNF quadcopter usually comes completely assembled, but without a controller. With BNF models, you’ll have to use the controller that you already have (if it’s compatible) or find a controller sold separately. One thing you should know is that just because a transmitter and receiver are on the same frequency that doesn’t mean that they’ll work together.

• ARF stands for Almost-ready-to-fly - ARF Drones are usually like quadcopter kits. They usually don’t come with a transmitter or receiver and might require partial assembly. An ARF drone kit might also leave out components like motors, ESCs, or even the flight controller and battery. The definition of an ARF drone kit is very broad, so whenever you see ARF in the title, you should read the description thoroughly.

Taking care of legal consideration

Before you get started with your drone (I know you must be excited) make sure you are updated with all the rules and regulations for what you can and what you cannot do with the drone, the restricted areas and the permission to fly near any private property.

• Various countries have their own rules and regulations for flying drones. For Example in the UK it’s Civil Aviation Authority (CAA) that restricts you from flying drones near airports or aircraft, keep the drone below 400 feet etc. Further you can refer to the UK link

• In the US it’s federal Aviation Administration (FAA) which has a code of not to fly above a group of people, never fly under influence of drugs and alcohol. Please refer to here

• Similarly, for various countries you have strict rules that need to be taken care of before making a decision of buying a drone. So, save yourself from getting disheartened of the fact that you cannot achieve the purpose for what you bought this drone.

Improve the drone flying skills

A lot of people think that drones are hard to fly, but the truth is, they’re really not. Anyone capable of using an iPhone or Android device is more than capable of flying a drone. However, this does not mean that drones are fool proof. Even the most advanced drones require some general knowledge if you want to avoid crashing or worse, losing your drone forever. So you need to improve your flying drone skills.

Where To Buy A Drone?

If you don’t know where to buy a drone, don’t worry. There are tons of online stores for drones that will ship to just about any major country. If you’re buying toy drones, the best place to go is Amazon or others below:

All of the main websites for buying drones.

• dji.com: The #1 in popularity and name.

• Amazon.com: A little bit of everything.

• horizonhobby.com: The leader in radio control airplanes, cars, quads, radios and more.

• amainhobbies.com: The great selection of RC Hobby.

Geographic Information System

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Geographic Information System (GIS) is an information system able to encode, store, transform, analyze and display geospatial information.

Image credit: geo.university

Geographic Information System Software

• ArcGIS Desktop: Extendable desktop suite to manage, visualize and analyze GIS data in 2D and 3D, including image processing. Includes ArcGIS Pro, ArcMap, ArcCatalog, and ArcGIS Online.
• DIVA-GIS - DIVA-GIS is a free geographic information system software program used for the analysis of geographic data, in particular point data on biodiversity.
• GeoDa - A free and open source software tool that serves as an introduction to spatial data analysis.
• GISInternals - Povidesdaily build packages and software development kits for the GDAL and MapServer.
• Global Mapper - An easy-to-use, robust, and genuinely affordable GIS application that combines a wide array of spatial data processing tools with access to an unparalleled variety of data formats.
• GRASS GIS - A free and open source GIS software suite used for geospatial data management and analysis, image processing, graphics and maps production, spatial modeling, and visualization.
• gvSIG - A powerful, user-friendly, interoperable GIS.
• JUMP GIS - An open source GIS written in Java.
• MapInfo Pro - A full-featured desktop solution to prepare data for web mapping applications and create presentation quality maps that combines data analysis, visual insights, and map publishing.
• Marble - A virtual globe and world atlas.
• OpenOrienteering Mapper - A software for creating maps for the orienteering sport.
• QGIS - A free and open source GIS.
• SAGA - Open source system for automated geoscientific analyses.
• SharpMap - An easy-to-use mapping library for use in web and desktop applications.
• TileMill - An open source map design studio, developed by a community of volunteer open source contributors.
• Whitebox GAT - An open source desktop GIS and remote sensing software package for general applications of geospatial analysis and data visualization.
• DIVA-GIS - DIVA-GIS is a free geographic information system software program used for the analysis of geographic data, in particular point data on biodiversity.
• Abc-Map - A lightweight and user-friendly Web GIS. Create, import data from various sources, export maps or share them online freely and easily.

Remote Sensing

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Remote Sensing is a set of techniques used to gather and process information about an object without direct physical contact.

• Active remote sensing are instruments that operate with their own source of emission or light, while passive ones rely on the reflected one. Radiation also differs by wavelengths that fall into short (visible, NIR, MIR) and long (microwave). Active remote sensing techniques differ by what they transmit (light or waves) and what they determine (distance, height, atmospheric conditions, etc.).

• Passive remote sensing are instruments that depend on natural energy (sunrays) bounced by the target. For this reason, it can be applied only with proper sunlight, otherwise there will be nothing to reflect. It employs multispectral or hyperspectral sensors that measure the acquired quantity with multiple band combinations. These combinations differ by the number of channels (two wavelengths and more). The scope of bands (visible, IR, NIR, TIR, microwave).

Image credit: mdpi

Remote Sensing Software

• eCognition - A powerful development environment for object-based image analysis.
• ENVI 🌟 - A geospatial imagery analysis and processing software.
• ERDAS IMAGINE 🌟 - A geospatial imagery analysis and processing software.
• Google Earth - A computer program that renders a 3D representation of Earth based on satellite imagery.
• Google Earth Studio - An animation tool for Google Earth’s satellite and 3D imagery.
• GRASS GIS - A free and open source GIS software suite used for geospatial data management and analysis, image processing, graphics and maps production, spatial modeling, and visualization.
• Opticks - An expandable remote sensing and imagery analysis software platform that is free and open source.
• Orfeo toolbox - An open-source project for state-of-the-art remote sensing, including a fast image viewer, apps callable from Bash, Python or QGIS, and a powerful C++ API.
• PANOPLY- Panoply plots geo-referenced and other arrays from netCDF, HDF, GRIB, and other datasets.
• PCI Geomatica - A remote sensing desktop software package for processing earth observation data.
• SNAP - A common architecture for all Sentinel Toolboxes.

Point Cloud Processing

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Point Cloud Processing is a huge number of tiny data points that exist in three dimensions(3D). If you could spit those points out of a scanner they would appear as a cloud. This can be used for mapping, perception, and navigation in robotics and autonomous systems. It can also be used in augmented reality (AR) and