International Journal

on Marine Navigation

and Safety of Sea Transportation

Volume 1

Number 2

June 2007

181

Multidimensional Presentation of Radar Image

M. Waz

Polish Naval Academy, Gdynia, Poland

T. Stupak & A. Szklarski

Gdynia Maritime University, Gdynia, Poland

ABSTRACT: The modern navigation radar has no 3D visualization creation possibility. Digital signal

processing technology progress gave the new possibilities in radar data transforming process to many kinds of

digital picture representation. The picture saving methodes was upgraded last time and tools used during

picture transformation become popular and useful. For instance the RSC (Radar Scan Converter) – digital

radar picture recording and transforming tool can be used to create new picture on line. The 3D radar picture

creating become easy and fast because of modern computer graphic techniques. The radar 3D digital picture

creating should be standardized with 3D digital chart creating by IMO, because the navigation near future will

be probably based on digital information created in digital devices.

1 INTRODUCTION

The 3 dimension visualization is used in marine

navigation systems. Echosonders and sonars working

in hydroacustic systems under water environment

present in three dimensions.

Often vector map used multidimensional

presentation occurs. This presentation is used in

aviation and under water navigation. The producers

offered wider package of 3D chart conform to IMO

requirements. In the nearest future 3 dimensions

presentation maybe obligatory presentation on

navigation systems display. Part of these systems

work with radar and radiolocation data is sending in

digital form. 3D presentation of radar picture require

new technology of radar target build. In first step is

necessary compile digital form of radar signal.

2 DIGITAL RADAR PICTURE

The most of modern marine radars present digital

visualization in Cartesian coordinate axes. R

The radar picture is projected on computer or

liquid screen in form of square matrix with the same

numbers of pixel in lines and columns. This is the

raster form and it is reading in computer memory

like bitmap. BMP- is the bitmap net presenting one

or three color layer (one – 256 level of gray; three –

256 level of: red – R, green – G, blue – B). In

CMYK computer graphic is possible to picture

record in four layers of colors. In modern marine

radars are used two or three basic color for marine

radar elements (target, water) and eventually one to

rest information (movement vector, boundary of

acquisition...).

Radar picture storage in computer memory like

raster is continues data compilation which is

observation place function and it is changing with

hydro meteorological conditions, seaside line and

different objects. Continuous data compilation may

be a regular point net presentation, recorded like a

vector. Net points take steady balance on radar

screen and have steady geographical coordinates.

Each point of radar picture is shown like following

vector coordinate which gives information about

target. More convenient is radar picture built like un

regular points net with discreet value, which in next

step can create lines or areas.

All coastal lines and points describes

characteristic elements of the marine area create

representative radar picture matrix [3], [4], [5], [6].

The basic task to 3 dimension picture create is

digital radar signal storage which each pixel

182

coordinates give. This radar picture will be storage

like vector collection for 3D representative:

→O

(1)

where:

( )













∈∧∈∧>∈<

>∈<>∈<

NKRW,, K,W

,,,,:W,,

λϕ

λϕλϕ

1800900

ϕ, λ – pixel coordinate;

W – gain level of radar target.

Or for picture in pole coordinate system:

→O

(2)

where:

( )













∈∧∈∧>∈<

>∈<>∈<

NK,ZRW,d, K,W

,Z,d,,:W,d,

αα

03600

– bearing (NR);

d – distance (d

3 THIRD RADAR PICTURE COORDINATE

The basic task during 3D radar picture create will be

third coordinate build. Marine radiolocation station

gives information about altitude coordinate of

observed and tracked targets, but the radar picture is

created in 2D coordinate system map with target

altitude information. The sample of 3D screen is

small dimension mobile radiolocation station

MMSR 3D (made by RADWAR) shown on Fig. 1.

3 dimension radar presentations required digital

form signal transformation and 3 dimension graphic

application (i.e. OpenGl)

Fig. 1. Radiolocation station MMSR 3D (RADWAR)

Modern navigational radar is working like 2D

unit. In this unit isn’t possible to altitude information

used. Is target altitude information necessary for

marine navigation purpose? Gain of target echo

depends of cross section. This parameter non linear

depends from target dimensions. Third dimension of

target can be received radiolocation power signal.

This solution gives better capability of radar picture

visualization and presentation. Digital signal

registration (i.e. HP 54501A – Navigation Department

M.U. in Gdynia) used can take digital information

about altitude characteristics from true object.

Digital analyze of these information give possibility

of plotting, tracking or searching object. Modern

computer visualization technique facility this

process. Radar picture can be stored in digital form

like vector with coordinates (α, d, W), where α and

d is bearing and distance to the elementary cell of

radar signal and W coordinate is amplitude of pixel

identity like radar target.[1]

Fig. 2. Video radar signal and its digital form

4 MULTIDIMENSIONAL RADAR PICTURE

VISUALISATION

Radar picture digital form storage gives possibility

of its visualization. Present computer visualization

technique opens a wide range of its solution.

Presented picture can be shown with important

elements gain from research or used points of view

(special color). In multidimensional visualization

important points are well visible on the screen by

operator.[2]

Bellow (Fig.3) 3D radar form of Gulf of Gdańsk

is compared with its 2D radar screen form. There are

shown weak and strong target. On the 3D picture

weak echo created by sea waves (noise) is visible

and it isn’t detected on 2 d screen. Gain level on

both figures is the same. Probably part of radar

picture elements important for research will be easer

detect on multidimensional presentation.

Fig. 3. 3D radar form

183

Multidimensional visualisation must be done in

real time. Its need computer program created 3D

pictures shorter then one radar scanner rotation (3 s).

The usage of OpenGL, DirectX library makes this

process possible.

5 DIRECTX TECHNOLOGY

If the radar signal is storage in 3D form for created

3D visualisation are used packed and programmable

interface (API – Application Programming Interface).

Thanks for it is possible 3D code application create

working operation system control. These API are

DirectX graphic library made by Microsoft It working

in accordance with vector graphic principles. One

object is described by same triangular (in program

DirectX) and its coordinates.

The most important is order all objects from

farthest to nearest. DirectX program offered Z-

Buffer algorithm done this task. It is memory

structure storage coordinate Z (W for radar picture)

each pixel. For each screen parameter W in the pixel

is compared with this value from previous screen.

Next step is texture mapping its mean added 2D

bitmap to 3D triangular objects. Minimum two

different dimension bitmap are used. When objects

closed to observatory is used bigger bitmap and

when distance to the object growing up the bitmap is

changing for smaller. The library builds faster radar

pictures in 3D structure.

Fig. 4. Gulf of Gdańsk 3D radar screen

6 SUMMARY

Modern navigational radar gives possibility 3D radar

picture visualization. Digital transformation of

electronic signals programs development created

possibility of radar data transformation to the

different digital form.

Used Radar Scan Converter radar picture can be

registered and transformed in real time.

Computer graphic application created easy

transformation radar picture to 3 dimension form.

3 dimension radar signal maybe used to radar

chart build in important for navigation safety areas.

These applications are needed to improve radar

visibility of small objects during meteorological

disturbances and created improvement of marine

safety used radar.

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