The difference between orthographic photography and oblique photography

The difference between orthographic images and oblique images lies in the shooting angle, ground coverage, ground resolution, three-dimensional information, application fields and so on.

1, shooting angle

Orthophoto: When acquiring an orthophoto, a camera or sensor takes an image at an angle perpendicular to the ground, which is also called vertical photography. This means that the objects in the image are vertically projected on the ground, which makes the image maintain a high geometric accuracy.

Oblique photography: Different from orthographic images, camera or sensor takes images at a certain oblique angle during oblique photography. This leads to great perspective distortion of objects in ground images, but it can provide more perspective information.

2. Ground coverage

Orthophoto: Orthophoto can provide a wide ground coverage due to vertical shooting, usually covering a large area. They are especially suitable for making maps and analyzing geographic information systems (GIS).

Oblique photography: Oblique photography provides a more detailed perspective of the target, but due to perspective distortion, oblique photography images are generally only suitable for relatively small areas, such as buildings or landscapes in cities.

3. Ground resolution

Orthophoto: Orthophoto usually has high ground resolution due to vertical shooting and correction processing. This means that the details on the ground can be clearly seen and accurately measured and analyzed.

Oblique photography: The image in oblique photography may have a low ground resolution, because the perspective distortion leads to the loss of details in areas far from the center. However, they make up for this shortcoming by providing more perspective information.

4. Three-dimensional information

Orthophoto: Orthophoto is corrected on the ground after collection, and it has a fixed proportion and direction relationship through registration to geographical coordinate system. Therefore, orthophoto can provide accurate ground coordinates and elevation information.

Tilt photography: Tilt photography provides more three-dimensional information, including the height, shape and texture of the target. Inclined photographic images can be used to make three-dimensional models, measure the height of buildings, and make visualization and virtual reality applications.

5. Application area

Orthophoto: Orthophoto is often used in cartography, urban planning, land use analysis, environmental monitoring and other fields because of its high geometric accuracy and wide coverage.

Oblique photography: Oblique photography provides more visual information, so it has important application value in urban planning, architectural design, landscape analysis, cultural heritage protection and other fields.

To sum up:

Orthophoto is suitable for large-scale geographical analysis and mapping, emphasizing the geometric accuracy of the ground; Tilt photography is suitable for application scenes that need detailed visual angle information and three-dimensional modeling. They have different advantages and applicability, and can be selected and used according to specific needs.