- Google Earth
- Google Maps
- USA Photomaps
These are the sites we will be using to compare different types of imagery for FORT 230 in 2019.
And adding the ArcGIS Online version.
This area in Lewiston, Maine is a favorite for hiking and observing nature. It’s near the city, but seems like it is way out in the country.
Today I started using the drone again. I did a demonstration for the Class of 1958 reunion. When I tried using the drone yesterday I had all kinds of problems, which led to two broken propellers! But I got it back together today. We were able to do some flights and take some pictures in spite of the worsening weather. I really need to get this going again.
Usually hillshades from a DEM are visualized from the northwest. Here I tried it both from 315 degrees (NW) and due south, 180 degrees. The results are very different. The topography of the lake appears inverted with the azimuth of 180. That is, the reservoir appears above the landscape.
Here is the contour map with a contour interval of 20 feet and an index contour every 100 feet. In ArcMap I made two separate contours.
The top map has an overlay of Landsat 8 imagery from April 13, 2016, which was downloaded from the Landsat Look viewer. It used the percent clip enhancement that eliminates the lightest and darkest areas and modifies the colors. Landsat is intended for medium scale use on a regional basis. Using successive images of the same area we can see changes in vegetation over time. It is not good for large scale work. The second map shows the same area, at the same scale with the ESRI true color base map.
This video from Oregon State University is one of the best explanations of how to interpret remotely sensed imagery. It talks mostly about aerial photos, but it applies to other kinds of imagery, too.
Following are notes on infrared imagery.
Here is a link to an infrared photography group on Flickr. It has black and white and false color imagery.
Near Infrared or False Color Maps for Study Sites
In this assignment we will use the NAIP imagery to generate true color and false color maps of our study sites. Here are semi-detailed instructions.
- Go to the PASDA Imagery Navigator (Go to www.pasda.psu.edu and choose Apps & Tools). Navigate to each of the study site points.
- Right click near each study site to bring up the PASDA Download Links. Choose the 2017 Statewide Infrared & Natural Color 4-band (1m). Click here to see what the screen looks like.
- Download the tiff files for NE Waynesboro, NW Iron Springs, and SW Caledonia.
- Extract them to the T drive like we did for the panchromatic imagery.
- Open ArcMap. Load each image layer twice and use the instructions below to make one of them color and one false color.
- Display the study points on the map as we did last week. Click here to download the geodatabase of the study points if you don’t still have it.
- Choose two of the study sites to map.
- Make two 1:9600 maps of each site similar to what we did last week.
- Export your maps as jpg files.
- Write a report on your website that includes your maps.
- Upload a link in Canvas to get credit.
- Answer the questions below in your report.
How to show two colors from one image layer.
The NAIP imagery has both true color and infrared false color in the same file. When downloading the tiff from PASDA you get four bands.
- red is 1
- green is 2
- blue is 3
- near infrared is 4
In ArcGIS the raster property wizard can reassign the bands as needed.
For natural color the display the bands in the symbology are set as:
- red — band 1
- green — band 2
- blue — band 3
Band 4 is not displayed
For CIR or false color, the bands should be shifted.
- red — band 4
- green — band 1
- blue — band 2
Band 3 is not displayed. Try experimenting by showing different combinations or just one layer. As long as the red band is near infrared you can experiment with the others.
Questions to Address in Your Report
- How does the vegetation differ between the two views?
- How does hardwood vs. softwood vegetation compare?
- How do bodies of water compare between the two views?
- What time of year is NAIP recorded? Does this have an effects on what you see?
We visited the sites on Monday, 8/27. It was a very, very hot and humid day! This year I added Pearl Springs instead of the Ralph Brock seedling orchard and golf course. It’s good to switch from time to time.
Presentation for the Penn State Mont Alto Offered Student Reception, April 7, 2018
Foresters spend a lot of time in the field studying forest conditions and carrying out management activities from tree planting to timber harvesting.
It is also important to be able to see the whole forest from a distance to save time and money, and to better understand the resources.
Here are a few resources that we use to study the forests of Pennsylvania that are free to use for everyone.
Starting in the 1930’s aerial photos were taken on film from airplanes flying in back and forth patterns to cover part of the landscape. Many of these photos taken by the USDA are now available at the Penn Pilot website. You can look at photos from all over the state at different time intervals. The images can be downloaded and georeferenced in a GIS. http://www.pennpilot.psu.edu/
Google Maps is an evolving source of current imagery. It is updated frequently, so you never know what you will get. If you link it to your Google account you get access to a variety of navigation tools. maps.google.com
Pennsylvania has a spatial data clearinghouse called PASDA, where there is a huge range or geographic data that can be viewed or downloaded. It is used by public agencies, private companies, and interested people. In forestry classes we often download or stream data from PASDA for GIS projects.
Some of the types of data we use include:
- panchromatic (black and white)
- true color at different times and resolutions
- false color or near infrared, good for studying vegetation
- hillshade, which is a shadowed view of the topography developed from lidar
- state and local roads
- soil type maps
- streams and watersheds
- state park, state forest and state game land boundaries
- digital elevation models (DEM) to make contour lines and study topography
- topographic maps
We also use satellite imagery, but that’s for another presentation.