gisc9302 – gis as a profession / thesis...

GISC9231 – Remote Sensing and Image InterpretationDeliverable 3: Georeferencing of Scanned

Aerial Imagery and Change DetectionFinal Report

Table of Contents1. Introduction 1

2. Purpose 1

3. Methodology 1

4. Procedure 2

5. Conclusion 19

6. Bibliography 20

List of Figures

Figure 1: The Third Canal in 1934……………………………………………………………………………………………………………………….2Figure 2: The Fourth Canal in 1934…………………………………………………………………………………………………………………….3Figure 3: Formation at Location A. …………………………………………………………………………………………………………………….4Figure 4: Feature B. ……………………………………………………………………………………………………………………………………………5Figure 5: Feature C…………………………………………………………………………………………………………………………………………..…6Figure 6: Study Area in 1921. ……………………………………………………………………………………………………………………………..7Figure 7: Feature B. ……………………………………………………………………………………………………………………………………………8Figure 8: Ship passing through the Third Canal……………………………………………………………………………………………………9Figure 9: Both Canals in 1921………………………………………………………………………………………………………………………………10Figure 10: Both Canals in 2003……………………………………………………………………………………………………………………………11Figure 11: Study Area. 1934 images atop on 2003 Image. ………………………………………………………………………………….12Figure 12: The Lands of the Fuller Plan in 1921…………………………………………………………………………………………………..14Figure 13: The Lands of the Fuller Plan in 1934…………………………………………………………………………………………………..15Figure 14: The feature in 1921 and 1934…………………………………………………………………………………………………………….16Figure 15: Georeferenced 1934 Imagery Overlaid atop the IKONOS satellite image ………………………………………..…17Figure 16: Georeferenced 1921 Imagery Overlaid atop the IKONOS satellite image……………………………………………18

List of Tables

Table 1: 1934 and 2003 Images Analysis…………………………………………………………………………………………………………….…13

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1. Introduction

Digital image processing involves the manipulation and interpretation of digital images with the help of a computer. The primary goal of this assignment was to analyze spatial differences and changes regarding the certain area near the Third and Fourth Welland Canals. Three types of digital images have been given to analyze: three scanned aerial images for 1934 year, four scanned images for 1921 year, and one multispectral image for 2003 year that has already been georeferenced. Thus, one certain area but in three different years should be analyzed for change detection during this assignment.

2. Purpose

To gain a practical ability to georeference aerial images, using ESRI’s ArcGIS, To gain a basic practical familiarity with the undertaking and reporting of a change

detection analysis.

3. Methodology

Three types of digital images have been given to analyze changes in three years: 1921, 1934, and 2003. Already georeferenced multispectral image has been given. It was needed to make georeferences for the rest images using Georeference tool in ArcGIS and detect changes that had appeared in the certain area in 1921, 1934, and 2003 years.

To georeference something means to define its existence in physical space. That is, establishing its location in terms of map projections or coordinate systems.

Using Georeference tool in ArcGIS we needed to find ‘control points’ in one not georeferenced image and connect it with the same ‘control points’ in already georeferenced image. As more points are involved, as more accurate georeference is. However, three points is usually enough.

Usage the Swipe Layer in Effects Toolbar allows effortlessly compare one image from another .

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4. Procedure

1934 Aerial Images (A4873_19, A4873_20 and A4873_21)

a) What was the operational status of each of the canals in 1934? Why do you draw this conclusion?

I think that the third canal (eastern canal) was no longer in usage in 1934. I can infer it by dried or partly dried chambers and locks (Figure 1).

Figure 1: The Third Canal in 1934.

By long shadows in the locks I can assume that there is no water there as well as in the reservoir supplies (slightly westerly from the locks) which used to regulate the water level in the locks by pumping water over the Ontario Lake to the chambers and locks.

The fourth canal was in usage in 1934. Figure 2 portrays that it had straight lines, and filled with water, gates are closed. All the bridges across the canal were already built and seem to be operational. Furthermore, I cannot notice any evidences of construction activity at that moment.

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Figure 2: The Fourth Canal in 1934.

Also, all buildings for maintenance and operating the canal were built in 1934 (at the bottom of the Figure 2).

Thus, the fourth canal was in usage in 1934, and the third canal was no longer in usage.

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b) Referring to A4873-20 Welland Canals 1934 (JPEG), what is the wedge shaped formation at location A? What are the striations?

This formation is situated between the fourth and the third canals (Feature 3). This feature is located adjacent to railroad and crossed by several roads or pathways. The formation has unusual wedge shape. There are striations which is the evidence of construction activity. Also, by shadow I can infer that the formation is not flat and has an elevation. Moreover, the north- eastern part of the feature is higher than south- western.

Figure 3: Formation at Location A.

I would assume that the formation is the earth embankment created during the canal or tunnel construction. This embankment is soil that has been excavated during the 4 canal construction.

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c) Again, referring to A4873-20 Welland Canals 1934 (JPEG), what is the linear feature at location B? What was its status in 1934 (was it actively being used)? What is your evidence?

This linear feature is situated at the south of the railroad and is crossed by the third canal. This feature discontinues by the canal and continues after crossing the canal. By huge shadow atop the feature I can infer that there is a depression. Consequently, this feature is a ditch excavated in the ground. It has equal width with canals’ locks. Therefore, the ditch is rather wide. This feature has unnatural straight shape- the sign of constructed object.

Figure 4: Feature B.

Thus, this linear feature is a part of railway tunnel under the third canal. I think that in 1934 it was no longer or rarely in usage. I can infer it by the vegetation on the railways at the right-top of the figure 4 (red circle). That is a sign of poor maintenance this part of railway road.

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d) Again, referring to A4873-20 Welland Canals 1934 (JPEG), why do you suppose the pond at C existed? Support your hypothesis thoroughly.

This feature has unique pattern and shape. By the tone and colour of feature I can assume that it is water (Feature 5).

Figure 5: Feature C

These two water features probably have been a part of one big pond that had been appeared because of canal activity or canal construction. If we appeal to earlier images of this area, this pond didn’t exist in 1921 (Figure 6). With canal 4 construction and canal 3 modification, man had intervened to ecosystem of this area and this pond has appeared. Narrow streams from the north to the south, as well as from the crop field at the west, have filled this pond (Figure 5). From the figure 5 we can learn that constructors have been trying to eliminate this pond by filling it up with soil (light and dark- tone striations).

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Figure 6: Study Area in 1921.

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e) Again, referring to A4873-20 Welland Canals 1934 (JPEG), what is area E? Justify your hypothesis.

This huge feature is located between two canals and has straight shape, divided by several zones which could be a sign of human activity (Figure 7). At the left of the feature there is a road. Also, there is a water streams that cross this area (dark curved lines).

The color of different parts of the area is different which is the sign of dry and wet soil. Boundaries of these areas are unnaturally straight. Moreover, there are straight vertical lines on these parts which could be crop rows. Thus, this huge area is a crop fields. Moreover, this crop fields could be abandoned because of canal construction. Referring to the previous question, ecosystem of this area has been changed due to the canal activity or canal construction.

Figure 7: Feature B.

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1921 Aerial Images (H20-1, H20-2, H22-25, H22-91)

f) What was the operational status of each of the canals in 1921? Why do you draw this conclusion? (5 marks)

The third canal was in usage, and the fourth canal was under construction in 1921. Figure 6 portrays that chamber locks of the third canal (yellow circle in figure 8) were full of water, locks had straight boundaries. Canal was well maintained. Furthermore, there is a ship passing through the 12 lock. Southern gate of the lock is opened.

Figure 8: Ship passing through the Third Canal

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The fourth canal surface is multicoloured (two- coloured actually since the image is black and white) which is an evidence that the canal wasn’t full of water (red rectangle in figure 9). Black coloured straight lines could be wet soil and white coloured straight lines could be dry soil. I can notice that gates separated one chamber from another as well as bridges were already built. That could mean that the fourth canal was already partly excavated.

Thus, the third canal was in usage, and the fourth canal was under construction in 1921.

Figure 9: Both Canals in 1921

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2003 Satellite Imagery (IKONOS Multispectral Imagery)

g) What was the operational status of each of the canals in 2003? Why do you draw this conclusion? (5 marks)

By analyzing the 2003 Satellite Imagery (IKONOS Multispectral Imagery) I can infer that the fourth canal was in active usage. It is full of water, has straigt lines, all supplies was well maintained. Furthermore, there were two ships passing the canal (red circles in figure 10).

Lets examine area within the yellow circle at figure 10. It is a part of the third canal. There is a gate separated two chambers from each other (at the center of figure 10). Water colour at the north from the gate is different from water colour at the south from the gate. That means that water from the south hadn’t been mixing with water from the north of the gate. Consequently, this gate had been closed for a long time. Another obvious evidence of closed third canal is huge vegetation that formed curved boundary of the third canal which is a sign of poorly maintained canal.

Figure 10: Both Canals in 2003

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Change Detection

h) Figure 1 above as well as H22-25 Welland Canal Locks 1921 (JPEG) and H22-91 Welland Canal Locks 1921 (JPEG) show the lock numbering system in 1921 for the 3rd canal. Create a table that shows how locks 11 through 24 are/are-not visible to our remote sensing platforms in 1934 and 2003. For each year, note whether the lock is visible, partly visible, not visible or not shown on the imagery. For non-visible locks, add a comment column to your table detailing why the lock is no longer visible.

Figure 11: Study Area. 1934 Images atop on 2003 Image.

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Number of Lock

1934 Images Comment 2003

Image Comment

11 VisiblePoorly maintained but

distinguishable. Area around the lock was partially submerged

Partly visible

Poorly maintained, vegetation, abandoned lock, flooded with water

12 VisiblePoorly maintained but

distinguishable. Area around the lock was partially submerged

Partly visible


13 Visible Poorly maintained but distinguishable

Partly visible



Partly visible



Partly visible



Partly visible



Partly Visible



Partly Visible


19 Partly visible

Only northern part of lock is visible. Lock has been rebuilt and changed

its direction from south west to south.

Not visible

Lock has been rebuilt. In that place. Actual 19 lock is hidden by vegetation.

Only

20 Not visible

Submerged due to 4 canal construction

Not visible Submerged due to 4 canal construction

21 Partly visible

Partially submerged, vegetation, poorly maintained, abandoned lock

Partly visible

Partially submerged, vegetation, poorly maintained, abandoned lock

22 Partly visible

No longer in usage, vegetation, poorly maintained, abandoned lock

Partly visible

No longer in usage, vegetation, poorly maintained, abandoned lock

23 Not shown Out of image boundary Not

visibleNo longer exists due to 4 canal

construction

24 Not shown Out of image boundary Not

visibleNo longer exists due to 4 canal

constructionTable 1: 1934 and 2003 Images Analysis.

Both images have been georeferenced and analyzed using Swipe Layer in Effects Tools of ArcMap. In 1934 and 2003 the third canal was no longer in usage. In 2003 there was much more vegetation around the locks than in 1934 which is an evidence of poorly maintained and abandoned canal. One lock is not visible due to submergence the area it was situated. Almost all locks in 2003 are not visible or hard to distinguish because of vegetation and poor maintenance of the canal. Nobody has been preventing nature from growing. In 1934 almost all

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locks are visible because not too much time passed after canal abandonment. Also, one lock is not visible due to submergence the area it was situated. Area has been submereged during the fourth canal construction.

i) Describe the changes within the lands of the Fuller Plan from 1921 through 1934 to 2003. Speculate why these changes occurred.

The lands of the Fuller Plan It are bounded by the Canadian National Railway (C.N.R.) and two roads. This parcel belonged to Reverend Thomas Fuller who originally had plans to subdivide the land for housing. The plan never came to fruition.

Figure 9 portrays that in 1921 there were few houses or barns, crop fields, pathways, and man planted trees (trees have particular order, not wild vegetation) within the Fuller Plan area (Figure 12). Consequently, this area was occupied and actively used for agricultural and other purposes. There was a construction of fourth canal at the west from the Fuller Plan in 1921. Also, Fuller Plan was crossed by tunnel.

Figure 12: The Lands of the Fuller Plan in 1921

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Fourth canal construction was operated in 1934. The third canal was already closed and abandoned. Figure 13 shows the lands of the Fuller Plan in 1934. There were no buildings in this area as well as crop fields. I assume that this area was abandoned. There were no crop fields, buildings, no signs of human activity within this area in 1934. Possibly, buildings have been dismantled, moved to another place then, and assembled again (it was common practice in wooden buildings construction). The land owner has left this area for some reasons. One of the reasons for this could be dissatisfaction with association with construction object or fear of ghosts from the Blue Ghost Tunnel.

Figure 13: The Lands of the Fuller Plan in 1934

j) What happened to the wedge shaped landform at location A of to A4873-20 Welland Canals 1934 (JPEG) that was visible in 1921 and 1934? Support your hypothesis.

Referring to the question b, this embankment is soil that has been excavated during the canal construction. Figure 14 portrays that the feature was brighter in 1921 than in 1934. It could be a sign of dry soil. In 1921 the 4 canal was under construction, and in 1934 it was already built.

By shadows examination in the north of the feature in the 1921 image, I can assume that this feature has an elevation. This feature is embankment of soil that has been excavated during the

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canal construction. However, this embankment in 1921 had less height than in 1934 (I can infer it by shadows as well). Also, in the 1921 image there are rail or road trails with vehicles (yellow circles in Figure 14) that carried excavated soil from the canal. These vehicles carried soil to the certain point and excavator moved soil to form embankment then.

Thus, this feature became higher in 1921 than in 1934 due to excavated soil.

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Figure 14: The feature in 1921 and 1934

k) Create two figures for your report that show (via screen save or formal ArcGIS layout) the georeferenced imagery overlaid atop the IKONOS satellite image. One Figure for the 1921 imagery and one for the 1934 imagery. (16 marks)

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Figure 15: Georeferenced 1934 Imagery Overlaid atop the IKONOS satellite image

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Figure 16: Georeferenced 1921 Imagery Overlaid atop the IKONOS satellite image

Both imagery have been georeferenced using Georeference tool in ArcGIS (Figures 15,16)

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5. Conclusion

Basic principles of change analysis as well as temporal space change have been obtained. Also, skills to georeference aerial images have been obtained.

It is crucial to be attentive during georeference and choose only permanent objects; for example, buildings, bridges, monuments, and so on. Change analysis strongly depends on the quality of georeference.

Also, knowledge of application remote sensing image interpretation has been obtained.

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6. Bibliography

1. Lectures GISC9231 – Remote Sensing and Image Interpretation

2. Remote Sensing and Image Interpretation / Thomas M. Lillesand, Ralph W. Kiefer, Jonathan W. Chipman – 2nd ed.

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