Aerial Photo Interpretation

Transcription

1 Aerial Photo Interpretation

2 Aerial Photo Interpretation To date, course has focused on skills of photogrammetry Scale Distance Direction Area Height There s another side to Aerial Photography: Interpretation Receives less emphasis in this course, but Photo interpretation is a huge part of photogrammetry & remote sensing

3 Aerial Photo Interpretation Photo Interpretation The act of examining photographic images for the purpose of identifying objects and judging their significance Ability to interpret information is affected by: Character of the imagery and the experience & knowledge of the interpreter Some of the best photo interpreters have backgrounds in earth sciences Photo interpreters (PI) behave much like detectives assessing various clues provided in a photo that point to some conclusion WWII - German radar facilities were nearly impossible to see on photos. Turns out the Germans often fenced them in, which had a unique shape.

4 Aerial Photo Interpretation In some disciplines, interpretation is the primary reason for aerial photos. Location of mineral deposits through interpretation Discovery of disease problems in forested areas. Assessment of food supplies from Landsat imagery National security Military applications are where photo interpretation is the most demanding Frequently don't know what you are looking for Objects of interest are frequently semi-hidden May never have seen the object before and hence, identification is difficult From May, 1942 to March 1945, V-Weapons were under observation by British photo interpreters. Rockets at Peenemunde were detected on aerial photos 12 months before they were used against England. Detected 96 steal and concrete sites for V- weapons on French coast. June 23, 1943

5 Aerial Photo Interpretation Many applications of image interpretation: 1) Land use/land cover mapping 2) geologic mapping 3) soil mapping 4) Agriculture 5) Forestry 6) Rangeland management 7) Water resources 8) Urban/regional planning 9) Wetland mapping 10) Wildlife ecology 11) Archaeology 12) Environmental assessment

6 Aerial Photo Interpretation How does one go about developing the skills necessary for effective photo interpretation? Useful steps 1) Much more information can be obtained from the 3 dimensional stereoscopic image than from single photos. 2) Interpretation should be done methodically. Interpret only one topic at a time. Work with the most familiar and work toward least familiar Develop an order of interpretation. For example - Transportation features - Drainage features - Natural vegetation features - Agricultural features - Rural & non agricultural features - Urban features - Heavy industrial features - Military features

7 Aerial Photo Interpretation Useful steps 4) Interpretation should begin with general items and proceed to the specific Look to center of the photo and work outward Evaluate broad regional patterns first (terrain, drainage, agriculture) 5) Proceed from the known to the unknown 6) Keep in mind the photographic qualities of a particular photo (Color, B&W, CIR) Some information may be obscured 7) Maintain a proper state of mind Don t get frustrated Weigh all evidence before making difficult interpretations

8 Aerial Photo Interpretation Suggestions for Effective Interpretation When possible, view photos in stereo Interpret familiar items first Remember to check the date of the imagery Know how film characteristics affect images o True color (VIS) o Panchromatic visible o Color infrared (CIR) o Black & white IR

9 Aerial Photo Interpretation Suggestions for Effective Interpretation Bring all of your life experiences to bear Look for a convergence of evidence Use key features & characteristics to guide interpretation Beware of Search Images

10 Aerial Photo Interpretation If this is your search image for an airport

11 Aerial Photo Interpretation you may have trouble finding lesser airports.

12 Important Characteristics Used in Interpretation The Art of Recognizing Specific Objects Size or Dimension Absolute Relative Shape Convergence of evidence Pattern Natural Man-made Tone (B&W) or Hue (VIS & CIR) Texture Overall Edge Shadows Association & Location

13 Important Characteristics Used in Interpretation SIZE (absolute & relative)

14 Important Characteristics Used in Interpretation SHAPE 2D shape on a single photo RR tracks vs. auto roads Country roads vs. interstates Baseball diamonds etc. 3D shapes in stereo RR tracks on gently sloping grades Roads and highways on much steeper slopes

15 Important Characteristics Used in Interpretation Pattern Spatial arrangement of objects whether man-made or natural Power lines vs. highways Clear-cuts vs. wildfire/blowdown Corn fields vs. orchards

16 Important Characteristics Used in Interpretation Tone (or hue/color) Often described as: uniform, mottled, banded... For a boundary: sharp, distinct, gradual, fuzzy B&W photos Tone ranges from black to white Soil moisture, vegetation type, film exposure, season, sun elev. all affect tone Color photos Hue (color), saturation, & brightness We can distinguish 100X more variations in color than shades of gray on B&W photos

17 Important Characteristics Used in Interpretation Sharp Continuous Texture (smooth, fine, coarse) Is the result of tonal changes that define a characteristic arrangement of tones EDGES

18 Important Characteristics Used in Interpretation Shadows Provide powerful clues for interpretation Profile shape Relative object size May cause false stereo in some situations (toward vs. away from the interpreter) Handy for identifying trees!

19 Important Characteristics Used in Interpretation Shadows Provide powerful clues for interpretation Profile shape Relative object size May cause false stereo in some situations (toward vs. away from the interpreter) Handy for identifying trees!

20 Important Characteristics Used in Interpretation Shadows Relative sizes of buildings & ID of other features

21 Important Characteristics Used in Interpretation Association & Location..plus all the other clues Industrial? What? Piles of black stuff RR tracks Electrical features Water port w/slip Large building Large smoke stack Another puzzler Convergence of Evidence

22 Important Characteristics Used in Interpretation Convergence of Evidence 1) No single piece of evidence is likely to be enough 2) By noting many items, evidence will begin to converge as some possibilities are discarded. See if you can figure this one out Aircraft Rescue & Fire Fighting Training Facility

23 Shape/Shadow Some times tree individual tree crowns or shadows can be seen on larger-scale aerial photography Silhouettes of forest trees For foresters, this is a valuable tool in producing cover type maps Aerial views of tree crowns

24 Common Tree Shapes

25 Shape/Shadow: Aerial views of tree crowns

26 Shape: Aerial views of tree crowns

27 Aerial Photo Interpretation: Drainage Patterns Dendritic Rectangular Parallel Radial Centripetal Trellis Deranged

28 Aerial Photo Interpretation: Drainage Features

29 Aerial Photo Interpretation: South Dakota Topographic Features

30 Aerial Photo Interpretation: Topographic Features Utah

31 Aerial Photo Interpretation Transportation Features

32 Aerial Photo Interpretation: Agricultural Features Iowa Wisconsin Wisconsin Iowa

33 Aerial Photo Interpretation: Urban Features New Orleans

34 Land Use/Land Cover: Anderson et. al Level I Level II A Land Use And Land Cover Classification System For Use With Remote Sensor Data

35 Urban Features URBAN / BUILT-UP Residential High density Low density Commercial / Services High/Low intens. Industrial Transportation/Utility Can you identify each?

36 Urban/Suburban: Much Smaller Scale Iowa

37 Suburban: CIR

38 Aerial Photo Interpretation: Some Practice Isle Royale

39 Aerial Photo Interpretation Minnesota

40 Aerial Photo Interpretation: Some Practice Wisconsin

41 Aerial Photo Interpretation: Some Practice Wisconsin

42 Aerial Photo Interpretation: Some Practice

43 Aerial Photo Interpretation: Some Practice Wisconsin

44 Aerial Photo Interpretation: Some Practice Wisconsin

45 Aerial Photo Interpretation: Some Practice Wisconsin

46 Aerial Photo Interpretation: Some Practice Minnesota

47 Aerial Photo Interpretation: Some Practice???

48 Aerial Photo Interpretation: Some Practice Iowa

49 Aerial Photo Interpretation: Some Practice

50 Aerial Photo Interpretation: Some Practice Iowa

51 Aerial Photo Interpretation: Some Practice Wisconsin

52 Aerial Photo Interpretation: Some Practice Minnesota

53 Aerial Photo Interpretation: Some Practice Minnesota

54 Aerial Photo Interpretation: Some Practice Wisconsin

55 Aerial Photo Interpretation: Some Practice

56 Aerial Photo Interpretation: Some Practice

57 Aerial Photo Interpretation: Some Practice Near IR Near IR CIR film shift. BG R

58 Aerial Photo Interpretation: Some Practice NIR RED GREEN What Color will the car be in CIR?

59 Aerial Photo Interpretation: Some Practice

60 Aerial Photo Interpretation: Some Practice Can you see the conifers?

61 Aerial Photo Interpretation: Some Practice

62 Aerial Photo Interpretation: Some Practice

63 Aerial Photo Interpretation: Some Practice

64 Aerial Photo Interpretation: Some Practice Near IR SWIR SWIR Near IR Shortwave IR SWIR ,4,3 shift. B G R

65 Aerial Photo Interpretation Curiosity, interest, & outside knowledge are extremely important. Above all, practice increases proficiency!