COMPARATIVE ANALYSIS OF SATELLITE STEREO IMAGES METHODS AND TRADITIONAL TECHNIQUES FOR ENVIRONMENTAL...

COMPARATIVE ANALYSIS OF SATELLITE STEREO IMAGES METHODS AND

TRADITIONAL TECHNIQUES FOR ENVIRONMENTAL RISK MONITORING

M.Caprioli a,, A. Scarano b, A. Scognamiglio c, R.Trizzino d

a POLITECNICO DI BARI, DICATECh, v. Orabona 4, 70125 Bari, Italy - [email protected]

b POLITECNICO DI BARI, DICATECh, v. Orabona 4, 70125 Bari, Italy –[email protected]

c POLITECNICO DI BARI, DICATECh, v. Orabona 4, 70125 Bari, Italy – [email protected]

d CNR, IRPI, v. Amendola, 70126, Bari, Italy – [email protected]

KEY WORDS: DEM/DTM, LIDAR, Satellite, Stereoscopic, Photogrammetry, Remote Sensing

ABSTRACT:

The aim of this research is to identify fast and low-cost “Change Detection” techniques.

This requirement stems from the need to operate in an efficient and timely manner, especially in case of natural disaster and battle

against building abusiveness and, on the other hand, to environment monitoring: coastal erosion, subsidence phenomena, misuse of

quarries, deforestation and desertification, etc.

In this regard, this survey aims to assess the possibility of using DTM constructed by satellite images rather than DTM extracted

through other techniques such as LIDAR and aerial photogrammetry. The results are very interesting and confirm the hypothesis: it

is therefore possible to investigate territory in a more quickly and effective way.

We have chosen, in line with the targets set, to focus the analysis on geographical areas particularly affected by environmental and

anthropic criticalities, territorial morphological changes, building abusiveness, etc.

The first study is located on an area near Fasano (BR) - Italy, that is a part of the Alta Murgia National Park. The second one is

located in a mountainous area in the Basilicata, Italian region particularly affected by episodes of territorial transformation for both

natural and anthropic causes.

1. INTRODUCTION

In the last years, land-cover monitoring has gained significant

importance especially in conjunction with the recent natural

disasters that have affected the Italian territory. The developed

research aims to provide fast and low-cost instruments that can

fulfill the needs related to an emergency management.

Secondly, these instruments are useful for the territory

government. Actually some abusive urbanization phenomena or,

on the other hand, abandonment of areas with consequent

raising of territorial degradation levels too often occurs today.

It becomes necessary to identify and monitor these changes in

order to fight and delete abuses, and safeguard the territory.

We want to demonstrate that to meet these requirements

through this research, you can rely on satellite technology,

which up to now is the only way to solve the time gap between

the immediate urgency of information and the opportunity to get

them in a very short term.

Furthermore, the “Change Detection analysis” is used to

determine and monitor the country changes over time, helping

to reduce the processing time of data through automated

procedures and providing information with improved qualitative

content.

For this you need to use the same area images taken at different

times; you can made this quickly and low-cost only with

satellite images. These ones are then compared in order to

identify all the territorial transformation through the use of

appropriate software that adopt a complex filter system to

eliminate non-significant changes (e.g. vegetation growth,

image noise, etc).

The availability of repeatedly updated data makes it possible to

develop a territory monitoring system that not only acts as a

supporting design decisional tool, but also as a way to verify

design strategies in case of unforeseeable events.

2. STEREO IMAGES

IKONOS® Pro 1-meter and 4-meter products are perfect for

projects requiring high-resolution imagery and positional

accuracy when ground control may be costly, difficult, or

impossible to acquire.

Providing a strong base for three-dimensional feature

recognition, extraction and exploitation, the product provides

two images with stereo geometry to support a wide range of

stereo imagery applications such as DEM creation and three-

dimensional feature extraction. Stereo products in epipolar or

map projections provide RPC camera model data.

The present study reports on the metric comparison between the

DEMs respectively realized with the Stereo aerial pair and with

the satellite Ikonos stereo pair, and another test with

photogrammetric DEM and a Lidar survey. In a short time we

will compare also GeoEye-1 stereo pair.

The satellite metadata are:

IKONOS METADATA

Sensor Type: Satellite

Sensor Name: IKONOS-2

Processing Level: Standard Geometrically Corrected

Image Type: PAN/MSI

Pan Resolution: mt 1.0

MSI Resolution: mt 3.28

Interpolation Method: Cubic Convolution

Multispectral Algorithm: Projective

Map Projection: Universal Transverse Mercator

mailto:[email protected]

mailto:–[email protected]



Datum: WGS84

File Format: GeoTIFF

Bits per Pixel per Band: 11 bits per pixel

Multispectral Files: RGB File

Spectral range

Pan 526-929 nm

Blue 445-516 nm

Green 505-595 nm

Red 632-698 nm

Near IR 757-853 nm

Launch date 24-Sep-99

Life Cycle Over 8.5 years

Revisit Time 3 days

Orbital Altitude 681 km

GEOEYE-1 METADATA


Sensor Name: GEOEYE-1


Image Type: PAN/MSI

Pan Resolution: mt 0.50

MSI Resolution: mt 1.64

Interpolation Method: Cubic Convolution

Multispectral Algorithm: Projective

Map Projection: Universal Transverse Mercator

Datum: WGS84

File Format: GeoTIFF


Multispectral Files: RGB File

Spectral range

(pan) 450-800 nm

Blue 450-510 nm

Green 510-580 nm

Red 655-690 nm

Near IR 780-920 nm

Launch date 06-Sep-08

Life Cycle 7 years

Revisit Time 3 days

Orbital Altitude 681 km

Figure 1. Test area Ikonos + Aerial

Figure 1 shows the test area, chosen in the Basilicata region for

its characteristics of landslide area, which was part of the

comparison indicated.

The Ikonos stereo pairs were used for the extraction of DEM by

automatic correlation, with different software (LPS, Socet Set,

Micromap) by geometric parameters of the satellite with the

relevant RPC.

The aero-photogrammetric stereo pairs were obtained using a

Wild 15/4 UAGA-F aerial camera with C=153.22 mm wide

frame of about 1: 16000 suitable for cartography at a scale of 1:

5000.

The cartography and its DEM were obtained using standard

procedures of Photogrammetric survey using LPS software by

Leica with well-known autocorrelation procedure.

Figure 2. DEM and ortophoto drapping (test 1)

Figure 3. Some Ground Control Point (test 1)

The second test was performed on the area of Fasano in Apulia

region with DEM extraction by Aerial photogrammetry with 8

m grid, provided by regional Gis, and a Lidar DEM with 1 m

grid produced by SIT s.r.l. company in Noci (BA).

Figures 2 and 3 show the three-dimensional model obtained by

drapping the images on the DEM obtained in the first test, while

figures 4 and 5 refer to the test area of Fasano with

determination of some of the profiles that have then been

extracted and compared in the tests performed.

Figure 4. DEM and ortophoto drapping (test 2)

Figure 5. DEM with some profiles (test 2)

3. COMPARISON

TEST 1

The comparison between the two products obtained in test 1

was carried out by examining some elevation profiles and a

number of test points throughout the area.

The profiles of this first test have been chosen in different parts

of the area and with particular attention to those parts which

could be more easily affected by landslides or by human

transformation of the territory morphology.

In figure 6 we show one of these profiles, where we can see the

basic overlay of the two DEM without particular significant

movements of the heights obtained with the two different

methods.

In figure 7 we show a detail of one of these profiles where the

difference between the two DEM is more visible due to the

different scale of representation, but in any case less than 1 m.

Figure 6. Comparison between profiles (test 1/a)

Figure 7. Comparison between profiles (test 1/b)

Figure 8. Comparison between control points (test 1)

Figure 9. Error in positioning of GCP (test 1)

In these first elaborations we have derived the DEM without the

use of the GCP but only with the satellite RPC, and we see a

systematic error in the positioning layout. (Figure 8 and 9 and

Table 1).

Figure 10. Control points in the second step on test 1

In the second step we repeated operations using some GCP

obtained with a campaign of GPS survey with Leica L1/L2

receiver, long time survey and post-processing with adjustment

procedure.

In this way we obtained the results described in Table 2 and

Figure 10. We can see that in this second step both the plan and

height errors have been significantly reduced from 3-4 m to less

than 1 m and from 1 m to 30-40 cm in height.

In figure 11 we show the 3D view of DEM.

Table 1 Control points without GCP.

X Y Z

Ikon 1 599150,935 4463237,198 725,024 Ikon 2 599297,519 4463199,118 704,934 Ikon 3 599571,338 4463566,454 799,892 Ikon 4 599349,550 4464724,453 564,610 Ikon 5 600371,615 4462620,327 683,075 Ikon 6 600479,332 4462530,172 675,404 Ikon 7 599846,754 4461978,045 465,860 Aer_1 599147,551 4463239,714 725,971 Aer_2 599294,043 4463202,581 706,190 Aer_3 599567,640 4463570,711 800,754 Aer_4 599344,798 4464728,404 565,313 Aer_5 600367,604 4462624,089 683,997 Aer_6 600475,440 4462533,914 675,667 Aer_7 599843,005 4461980,968 467,047

X Y Z Ikon-Aer_1 3,384 -2,516 -0,947 Ikon-Aer_2 3,476 -3,463 -1,256 Ikon-Aer_3 3,698 -4,257 -0,862 Ikon-Aer_4 4,752 -3,951 -0,703 Ikon-Aer_5 4,011 -3,762 -0,922 Ikon-Aer_6 3,892 -3,742 -0,263 Ikon-Aer_7 3,749 -2,923 -1,187

Table 2 Differences in Control points with GCP.

X Y Z

X Y Z Ikon-Aer_1 -0,516 0,984 -0,047 Ikon-Aer_2 -0,424 0,037 -0,356 Ikon-Aer_3 -0,202 -0,757 0,038 Ikon-Aer_4 0,852 -0,451 0,197 Ikon-Aer_5 0,111 -0,262 -0,022 Ikon-Aer_6 -0,008 -0,242 0,637 Ikon-Aer_7 -0,151 0,577 -0,287

Figure 11. 3Dview of DEM

TEST 2

In the second test in the Fasano area we verified that there is a

substantial congruence of the Dem extracted with aerial

photogrammetric method and the LIDAR one.

In figures 12 and 13 we can see the trends of the two LIDAR

and photogrammetric profiles which are completely overlayable

and comparable, maintaining the deviations well below 1 m in

most of the analysed territory.

Figure 12. Comparison between profiles (test 2)


In the images below, we have highlighted a case of greater

discordance in the heights.

In this case, in figure 14 we find differences of approximately 6

m whereas in figure 15 we find differences of over 8 m between

the two compared DEM.


Figure 15. Zoom on new building (test 2)

Also the map of the height difference clearly shows the areas for

amendment of the land as highlighted in white in Figures 16

where the map has been built with 6 categories of height, and

even more in Figures 17 where the different representation

categories of height are only 2.

Figure 16. Differences between two DEMs (cat. 6)

Figure 17. Differences between two DEMs (cat. 2)

It is very interesting to note in the profile of figure 14 the

difference of height both in the profile and in the map of the

height differences, between the DEM of different time, after the

construction of a new shopping centre.

This confirms the ease of use of these comparisons to determine

significant transformations of the territory either man-made like

in this case or as a result of natural events.

TEST 3

The next test was performed by using a GeoEye stereo couple of

a part of the territory of Fasano (Brindisi). It is the same part as

test 2 chosen to be able to make several comparisons amongst

the various DEM analysed and highlight the characteristics of

each one, making a suitable comparison.

In this case the test area is located in the immediate vicinity of

the height difference which is located in the territory of Fasano

due to the presence of the hilly area called the “Selva” which

reaches a height of about 400 m above sea level.

The stereo couple used was acquired on 26th March 2012 and

below is reported an extract of the satellite characteristics:

Creation Date: 03/26/12

Product Work Order Number: 12F00593_1

Product Order Number: 3804207

Customer Project Name: fasano

Ground Station ID: RGS19

(…)

Product Order Area (Map Coordinates in Map Units)

Coordinate: 1

Map X (Easting): 705076.5892162491 meters

Map Y (Northing): 4527225.7840325935 meters

Coordinate: 2



Coordinate: 3



Coordinate: 4




Sensor Name: GeoEye-1

Product Line: GeoStereo


Image Type: PAN/MSI

Interpolation Method: Nearest Neighbor

(…)

Datum: WGS84

Product Order Pixel Size: 0.5000000000 meters

Product Order Map Units: meters

MTFC Applied: Yes DRA Applied: No Media: Electronic

Product Media Format: Electronic File Format: GeoTIFF

TIFF Tiled: No Compressed: No


The DEM (density 0.50x0.50 m) used for the comparisons was

extracted by photogrammetric self-correlation from a survey

carried out in the month of September, 2006 by the SIT of Noci

(BA, Italy) with DMC 01-0037 system restored with SOCET

SET 5.2 software.

The LIDAR survey and the extracted DEM (density 0.50x0.50

m) is that has been used in the second test, and has been carried

out in June 2010, with LEICA ALS50/II system treated with

LEICA FPES-IPAS-ALS-PP software.

Also in this test, we have carried out a series of cross

comparisons between the three DEM available, obtaining good

results, which back up the hypothesis of using the stereo-

satellite couples to obtain maps of the changes of the territory,

in a quick and relatively cheap way.

First, a DEM has been extracted from the stereo couple using

the RPC and Leica Photogrammetric Suite (LPS) software,

relevant a small part of the image.

The DEM obtained has a step of 0.50 m, coherent with the aero-

photogrammetric DMC and the LIDAR one.

In the case of this third test we have made the comparisons by

using the analysis functions, of the raster of the Arcgis software,

to obtain several maps of the differences of height, between the

two DEM. Then we made also a comparison between

significant profiles extracted in the same area.

The height difference obtained, between photogrammetric

method (DMC) and stereo couple GeoEye, are shown with in

“map of differences”, represented by classification into different

classes to make it easier to understand, using range of 1 m

As can be seen in Figure 18 below, the percentage of pixels

with height difference exceeding 1 m is very limited, indeed the

grey pixels are 88% and the black or the white pixels are 12%

of the whole image.

Figure 18 Differences map DMC-GEOEYE (range 1 m)

If we move the range to 2 m the percentage of pixels, with a

greater difference, drops to a few units (Figure 19).

Figure 19 Differences map DMC-GEOEYE (range 2 m)

The following image (Figure 20) shows more clearly the area

most affected by the difference in the overlying orthophoto: the

areas in red (positive) and yellow (negative) are those with a

difference in excess of 1 m.

Figure 20 Orthophoto with differences map (DMC-GEOEYE)

Then we made further maps of the height differences between

the photogrammetric DEM (DMC) and the LIDAR one, to

compare the different maps to see how much the results

achieved differ from one another.

What we see below (Figure 21) is the image of this new map of

the differences where we see the substantial similarity with the

one we have just seen. The areas with main differences between

LIDAR and DMC are the same as the ones where we have

found differences between DMC and GeoEye.

Figure 21 Orthophoto differences map (DMC-LIDAR)

In order to complete the comparison, we then compared the

DEM extracted from GeoEye and those of LIDAR, as can be

seen in the image below (Figure 22) and here too the areas with

greater differences overlie those of both the above comparisons.

Figure 22 Orthophoto differences map (GEOEYE-LIDAR)

In all cases the main differences are thus present in the same

areas, we, therefore, tried to interpret what they were due to by

making significant profiles in those areas in particular.

In the images below (Figures 23-24) we can see the case of

surfaces with differences allocated to modification of the

vegetation.

This differences are due to restitution operations where the

operator corrects the results of automatic correlation “bringing

to ground” the heights of the tree-tops.

Indeed, when the DEM was produced only by automatic

correlation on satellite stereo-pair we get a height of the DSM

on the tree-tops.

Figure 23 Profiles (GEOEYE-LIDAR) vs (GEOEYE-DMC)

Figure 24 Detail of Figure 23

We finally point out in the image that follows (Figure 25) the

same areas with different height difference, exceeding 1 m, with

red (positive) and yellow (negative) in transparency on the

ortofoto.

These differences relate precisely to the buildings that are not

reported in the DEM extracted with photogrammetric methods

and which are present both in LIDAR and in GEOEYE stereo-

pair DEM.

Figure 25 Orthophoto (DMC-GEOEYE)

4. CONCLUSION

In conclusion, the first test has verified the procedure for the

extraction of DEM from satellite stereo images by using both

the parameters supplied with the stereo pair (RPC) and the

ground control points.

The second set of tests, in addiction, shows very good results in

extraction of DEM both in Aerial photogrammetric method and

in LIDAR traditional method.

The availability of GeoEye-1 stereo pair allowed to perform

further test reported in this paper. The results encourage the use

of satellite stereo-pair DEM for the detection of changes,

especially in order to know immediately the consequences of

natural disasters and to search environmental transformation

and abuse.

This method has been tested on small areas but it can be easily

extended to larger ones.

The main benefits of using stereo pair are the repeatability and

the immediate detection of changes in the area both for natural

events and human ones too, that allows early recognition of

environmental risk situations, and make it possible to adopt

appropriate remediation and early warning measures.

The availability of repeatedly updated data makes it possible to

develop a territory monitoring system that not only acts as a

supporting design decisional tool, but also as a way to verify

design strategies in case of unforeseeable events.

5. ACNOWLEDGEMENTS

The authors thank the company S.I.T. (Sistemi Informativi

Territoriali) - Noci (BA), for collaboration on tests, and

PLANETEK – Bari.

6. REFERENCES

Baudoin A., Goudy P., Rouze M.: “The Pleiades Program”,

Joint ISPRS Workshop “High Resolution Mapping from

Space”, Hannover, 2001.

Dial G., Grodecki J.: “IKONOS Accuracy without Ground

Control”, Pecora 15 / Land Satellite Information IV / ISPRS

Com. I, Denver, 2002.

Grodecki J.: “IKONOS Stereo Feature Extraction - RPC

Approach”, ASPRS, St. Louis, 2001.

Jacobsen K.: “Mapping with IKONOS Images”, EARSeL,

Millpress, Prag, 2002.

Jacobsen K.: “DEM Generation from Satellite Data”, EARSeL

Ghent, 2003.

Hanley H.B., Yamakawa. T., Fraser C.S.: “Sensor Orientation

for High Resolution Imagery”, Pecora 15/ ISPRS, Denver,

2002.

Crespi M., Capaldo P., Fratarcangeli F., Nascetti A., Pieralice

F.: "DSM generation from very high optical and radar sensors:

problems and potentialities along the road from the 3d

geometric modeling to the surface model", IGARSS, Honolulu,

2010.

Crespi M., Capaldo P., Fratarcangeli F., Nascetti A., Pieralice

F.: "Matching strategies for DSMs exstraction in urban area

from high resolution satellite imagery", EARSel, Ghent, 2010.

Crosetto M., Pérez Aragues F.: “Radargrammetry and SAR

interferometry for DEM generation: validation and data

fusion”, CEOS SAR Workshop, ESA-CNES, Toulouse, 1999.

Leberl F.W.: “Radargrammetric image processing”, Artech

House, Norwood, 1990.

Li Z., Zhu Q., Gold C.: “Digital terrain modeling: principles

and methodology”, CRC Press, Florida, 2005.

Méric S., Fayard F., Pottier E.,:"Radargrammetric SAR image

processing", Pei-Gee Peter Ho (Eds.), Geoscience and Remote

Sensing, Intech, 2009.

Raggam H., Perko R., Gutjahr K.: “Investigation of the Stereo-

Radargrammetric Mapping Potential of TerraSAR-X”, 29th

EARSeL Symposium, Chania, 2009.

Toutin T., Gray L.: “State-of-the-art of elevation extraction

from satellite SAR data”, ISPRS Journal n. 55, ELSEVIER,

2000.

COMPARATIVE ANALYSIS OF SATELLITE STEREO IMAGES METHODS AND TRADITIONAL TECHNIQUES FOR ENVIRONMENTAL...

Documents

Transcript of COMPARATIVE ANALYSIS OF SATELLITE STEREO IMAGES METHODS AND TRADITIONAL TECHNIQUES FOR ENVIRONMENTAL...