In recent years, aerial photography has been dynamically evolving a tool for ecological management. Historically, the process of management and ecological monitoring involved aerial photographs interpretation which was time-consuming, subjective and required trained personnel.
Due to this, new approaches were used in collecting this ecological information. There are several challenges and benefits of using aerial photography for ecological management as it will be discussed shortly.
It is worth noting that aerial photography use in assessing and map landscape is important in the management of an ecosystem. Aerial photographs are often ideal for small ecosystems and they have many advantages in this field of study.
Challenges of aerial photography
The advantages of aerial photography are many, there are challenges that are specific while using them, this is in relation to interpreting an aerial photograph manually.
This technique relies entirely on the experience of an interpreter and many times it is subject to inconsistency and error.
Therefore, new approaches are needed to eliminate this difficulty associated with the analysis of an aerial photograph using traditional methods. This is motivated by the recent development via new techniques of analysis.
What is aerial photography?
Aerial photography refers to a collection of photographs captured from a high altitude usually through drone photography or on an aircraft.
The camera used in aerial photography is of fundamental importance as it must take features of objects from a great distance, therefore, their focal length fixes to focus reflectance from an infinite distance away.
Aerial photographs are grouped based on their geometry; these are either oblique or vertical. vertical photographs are taken focusing on the object directly overhead whereas oblique photographs are deliberately taken at an angle to the ground.
Aerial photographs capitalization
Traditional film photography can be digitized through scanning, this converts analog images into digital files usually represented in pixels. However, the inherent disadvantage of scanning photographs is the possible loss of radiometric or tonal variations and spatial resolution.
Basic photographic errors
Despite the great use of aerial photography, it’s worth noting that errors do occur at times during the collection and digitalization of photographs and hence limiting their use.
However, these inaccuracies may not always render aerial photographs entirely useless, understanding the main causes of error is crucial to accurate analysis. Errors are categorized as either radiometric or geometric in origin, and either random or systematic.
Error correction
For most mapping and digital classification purposes, the use of orthorectification features to correct the displacement errors due to geometry is necessary to provide a spatial reference.
Interpreting aerial photographs
1. Tone or color
Variation and the relative difference in tone and color on photographs are the main aspects that enable feature identification. They can be used too to make inferences to certain feature’s condition and state.
2. Size
An object’s absolute and relative size or feature are crucial not only to identify natural and cultural features, it may also be used to make ecological inferences about the features being identified.
In ecological application, the significance of size is directly linked to spatial scale which is one of the fundamental components in ecological pattern understanding.
3. Shape
This is specifically useful in recognizing cultural features, which usually have certain geometry and identifiable edges as well as many other distinct forms for given features.
4. Texture
One factor useful to the landforms is the Image texture. In an aerial photography, for instance, the texture may be used to present several biophysical features such as mountains, cliffs etc.
5. Pattern
A pattern refers to the spatial arrangement of physical features or any patches over coarser scales. Spatial features may be systematic or random and often distinctive for many specific natural features.
6. Shadow
This may help in identification of a feature by giving more information about an object or features in terms of shape, height, and orientation.
New approaches to aerial photography analysis
With recent development in technology, new methods such as digitalization of image enhancement and classification have become very important for aerial photography have greatly helped in eliminating problems faced by traditional photo interpretation.
The main advantage of this automated digital techniques is that it enables an explicit analysis of an individual characteristic of a photograph.
Accuracy assessment
Any analysis or classifications’ value entirely depends on its accuracy. This can be estimated by comparing the image and reference data derived from the field with the classified photographs.