Visual Representation of Windfarms

Transcription

1 Visual Representation of Windfarms Technical Session 2: Getting the pictures out of the camera (and what to do with them) Ian McAulay

2 SNH Requirements

3 For each viewpoint baseline photo cumulative wireline 75mm wireline (53.5 wide) 75mm photomontage (53.5 wide) Panoramic JPEG photomontage for digital viewer 75mm photomontage (27 wide)

4 Different projections Cylindrical Projection: baseline photo cumulative wireline Panoramic JPEG photomontage for digital viewer Planar Projection: 75mm wireline (53.5 wide) 75mm photomontage (53.5 wide) 75mm photomontage (27 wide)

5 Single frame Planar Projection

6 Planar Projection Wider field of view but still planar

7 Multiple frames Planar Projection

8 Cylindrical Projection

9 Reconstructing the Perspective

10 Reconstructing the Perspective

11 Workflow

12 This is the way Envision do it. It s not the only way you can do it. These are not the only tools you can use.

13 Workflow DTM data Photo parameters Windfarm model Photos Panoramic wireline Rendering Photo panorama Layered Photoshop file 53.5 Planar wireline 90 Cumulative wireline 90 Baseline photo Panoramic JPEG montage 53.5 Planar montage 27 Planar montage

14 Panoramic Wireline Provides geometric framework for matching photomontage Envision usually work with 180 or 360 panoramas Envision standard resolution is 36,000 x 3000 pixels

15 Photo Panorama Constructed semi-automatically from separate photo frames Many software solutions for stitching Envision have used PTGui and Hugin successfully

16 Stitching Software Must allow inspection/correction of control points Must blend frames smoothly without obvious blurring Must support wide output images Must deliver geometrically reliable results

17 Single frame as taken Reprojecting

18 Reprojecting Single frame reprojected to cylindrical

19 Reprojecting All panorama stitching software reprojects the individual frames as part of the stitching process Better software also corrects lens distortion Hugin can also act as a standalone reprojector

20 Stitching (PTGui)

21 Control Points

22 Control Points

23 Matching Wireline is the geometrical framework for matching Adjust photo to fit wireline (not the other way round) Use terrain and as many reference objects as you need Reference objects may be well away from main direction of view

24 Matching

25 Matching

26 Matching Terrain provides a good reference for matching in upland areas Terrain is useless in flat areas! Identify likely reference objects in the view Find coordinates for them (Google Earth is good for this) Model them as additional objects in the wireline

27 Matching If it s impossible to get a good match on all the reference objects at one, something may have gone wrong Check that the viewpoint coordinates are right (transposed digits?) See if the coordinates look reasonable on a map Find the viewpoint on Google Earth and double check that way

28 Reality Bites YOUR CAMERA IS NOT LEVEL!

29 Levelling/Straightening Minor levelling errors manifest as curved panoramas Unavoidable within limits of accuracy of equipment Fix in Photoshop!

30 Straightening

31 Straightening

32 Rendering Match between wireline and photo establishes and verifies perspective parameters Parameters can go straight into rendering software to produce shaded image of windfarm for montaging Envision variously uses POVray, V-Ray and Sketchup with final tweaks in Photoshop

33 Montaging

34 Montaging

35 Montaging

36 Finished Images baseline photo cumulative wireline 75mm wireline (53.5 wide) 75mm photomontage (53.5 wide) Panoramic JPEG photomontage for digital viewer 75mm photomontage (27 wide)

37 Finished Images Baseline photo: Crop from photo layer of layered file More than one if more than 90 needed

38 Finished Images Cumulative wireline: Crop from wireline layer of layered file More than one if more than 90 needed

39 Finished Images 75mm wireline (53.5 wide): Generate separately as planar projection (Reprojecting line drawings makes them slightly blurry)

40 Finished Images 75mm photomontage (53.5 wide): Extract from merged montage and photo layers of layered file Reproject to planar using Hugin

41 Finished Images Panoramic JPEG photomontage for digital viewer: Extract from merged montage and photo layers of layered file Crop to size

42 Finished Images 75mm photomontage (27 wide): Crop down from 53.5 photomontage

43 Page Layout Image and page sizes are fully specified by SNH The Viewpoint Pack is A3 All other visualisation pages are half A1, 841 x 297 mm

44 Page Layout baseline photo cumulative wireline Images 820 x 130 mm Page half A1, 841 x 297 mm

45 Page Layout 75mm wireline (53.5 wide) Image 820 x 260 mm Page half A1, 841 x 297 mm

46 Page Layout 75mm photomontage (53.5 wide) Image 820 x 260 mm Page half A1, 841 x 297 mm

47 Page Layout 75mm photomontage (27 wide) (For viewpoint pack) Image 390 x 260 mm Page A3 (420 x 297 mm)

48 Printing Minimum image resolution 300 ppi (pixels per inch) Check sample prints for colour balance and legibility (Slight over-sharpening of images is sometimes required for printing)