Lab 1

The approximate ground coverage visible if there is a 60% overlap would be 1337804 ha (given above) * 0.4 = 535121.6 ha. This is because the overlap is 60%, which means that 60% of the area covered by one photo is also covered by the overlapping photo. So, the effective coverage of the stereo pair is 100% – 60% = 40% of the area covered by one photo.

The major activities shown in the photos include neighborhoods, rivers, factories, areas of tree cover, and land used for recreation like golf courses, etc. I made these determinations by looking at the aerial photos and seeing the different zoning areas, as well as observing the images through the stereoscope. Also, using size, shape, patterns, texture, color and knowing the site details helps with identifying where each major activities occur.

Knowing that the photos were taken in October, we can determine that the trees in the upper half of the images are deciduous and evergreen. We can tell them apart because as the winter months approach, the deciduous trees lose their leaves and sometimes turn red, and evergreens keep all their pine/leaves. Looking at the photo, we see areas where trees are significantly redder than their surroundings, telling us that deciduous trees lie in that area. The spatial distribution between the different tree types are all randomly distributed with clumps of deciduous trees residing in multiple areas.

The stereoscope allowed us to see the image in 3D, further letting us understand the details of the image and letting us see more of the shape and size of the aerial view. The stereoscope also aids in the interpretation of topographic features, such as hills, valleys, and slopes, so we can better understand the relief and elevation changes in the landscape. Stereoscopic viewing allows us to have the ability to recognize fine details in the images. This is especially important when recognizing objects or features that may be obscured or challenging to determine in flat, two-dimensional representations.

The length of the edge of the oil storage facility is 12 cm. Since we know that the length of the edge is 1125 m, we can convert cm to m to get 0.12 m for the map scale. 0.12 m/ 1125m we simplify to get 1:9375 as a scale.

The economic activities that I observed in these photos are dams. These dams are distinctly visible in these air photos because the water shifts from a dark color to a lighter, brighter color and then dark again in two specific areas. I assume these have to be dams because concrete reflects differently than water. Logging roads are also present, as these roads can be spotted due to differences in reflectance. The shape and color of these economic activities are what allowed us to spot these differences in landscapes. For example, roads are way brighter in photos than vegetation, and so are urban areas, making them easy to spot in the aerial photos.

The BC 5678 photos are older because there seems to be less development than the 15BCB90130 photos. In the BC5678 photos, there are no dams, not as much development, and also way fewer roads. The river morphology is also a lot different in 1975 compared to 1990. In the BC5678 photos, the river is wider and less contained, while in the 15BCB90130 photo, there is more development around the river, making it less wide and more human-influenced. The dam is also limiting the amount of water that goes downstream making the river more contained than the older photos. The shaping of the river also caused an alluvial plain to form at the bottom of the photo, which means that BC 5678 is an older picture due to the alluvial plain taking time to form.

The larger scale picture is the BC 5678 photo. It is a larger scale because the residential areas of the photo seem a lot bigger than the other photos, meaning that it is more zoomed in, creating a larger scale.

Some characteristics that could help me to determine the different ages of the clear-cuts are the color of the trees, and the patterns of the trees. In Google Earth, we see a different hue of color in all the trees. Darker trees represent trees that are a lot older and more packed together. Lighter hues of trees mean younger trees. Since clear-cut forests are used to harvest trees, they usually contain one species, so there is no need to determine if there are multiple species. It is harder to decipher younger trees because they have yet to take shape. So, areas that are less dark and more open are areas that just got cut, and new trees are being planted.

 There is more historical imagery available at a smaller scale. This is because historical data at a larger scale is less available than data that can be stored at smaller capacities, like smaller-scale maps. Also, more rural areas tend to have less historical imagery because there isn’t much use for them. Demand from users can also influence the availability of historical imagery.  Going to the technical side, Google Earth often aggregates data from various providers, and the availability of historical imagery can be influenced by the partnerships and agreements Google has with these providers. The changes that are from Google Earth that would be difficult to observe from air photos include temporal scales, global coverage, and regular updates. Google Earth allows users to view historical imagery, making it better to observe changes over time. Also, Google Earth covers the whole world, so it is easier for users to collect data worldwide. There are always changing structures, so it is way easier to update in Google Earth than in air photos. Airphotos, on the other hand, can contain high-resolution, specialized maps and local surveys. Looking at the air photos, there is definitely a higher resolution on those than Google. Also, you are able to get different maps in air photos like infrared rather than just satellite data in Google Earth. For a specific location, local aerial surveys might be more comprehensive and tailored to the specific needs of a project.