lecture_3_mapping and scales.pdf

8/15/2019 Lecture_3_Mapping and Scales.pdf

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Mapping

Dr Ahmed Ragheb SCM 221 – Planimetric Surveying 1Lecture 3

Faculty of Engineering and Technology

Structural Department - Year 1

Dr Ahmed Ragheb

Planimetric Surveying 1)

SCM 22



Mapping


Basic map

1

Key Map

Map Titleم لوحة

Map

no.



Mapping


Project

Owner

Surveying Works

Map title

Scale

Map No.

Date

Information Table

2



Mapping


Computer Advantage in drawing maps

1- No deformation in storage

2- Easy to store

3- Easy to duplicate and plot

4- Any modification can be done easily5- Choosing the appropriate scale

6- Faster than manual methods

7- Any accuracy required

8- Less required time for production

9- Deals with coordinates

3



Mapping


Map Classification

A) According to purpose

1- Detail Maps (all natural and artificial features)

3- Engineering Maps (design and construction)

4-

Topographic Maps (terrain mapping)

5- Geological Maps (soil and surface rocks)

6- Geodetic Maps (taking Earth’s curvature into consideration)

7- Metrological Maps (temperature, wind and humidity)

8- Tourism Maps (leisure, museums, shopping, directions)

9- Marine Maps (water depth)

4

2- Cadastral Maps (land ownership boundaries)



Mapping


B) According to material

Ao, A1, A2, A3, A4, Ao Special roles

1- Paper Map

2- Water Proof & Thermal Map

3- Transparent Map

C) According to color

1- Black and White

2- Colored

D) According to size

5

Map Classification



Mapping


Scale

E) According to scale

1- Large Scale 1:100, 1:250, 1:500 (Detail Maps)

2- Medium Scale 1:1000 (City Maps), 1:2500 (Cadastral Maps),

1:5000 (Base Maps)

3- Small Scale 1:10000, 1:25000, 1:50000, 1:100000,1:500000, 1:1000000 (Geodetic & Topographic Maps)

6

1- Purpose of map

2- Importance of project

3- Required accuracy

4- Size of map sheet

Factors affecting choice of map scale



Mapping


North Directions

1- Geographic (True) North

Has to be drawn on any map for orientation

Tangent to the meridian passing by the

point towards North Pole

2- Magnetic North

It is the direction pointed by the

magnetic needle of the compass

- Changes from one point to another

- Affected by any magnetic field

- True North – Magnetic North = Magnetic Declination

7



Mapping


3- Grid North

- As tangent to meridians are not parallel, then North

directions are not parallel

4- Arbitrary (Assumed) NorthAssumed in any direction

- Use only one North for the whole surveyed area which

is the tangent to the mean meridian of surveyed area

8

North Directions



Mapping

Dr Ahmed Ragheb SCM 221 – Planimetric Surveying 1Lecture 3 9

Map Arrangement

If no. of maps (n) > 1

Maps are arranged:Numerical

Alphabetical

Alpha-numeric

1

654

32

97 8

A

FED

CB

IG H

A-1 A-3A-2

1 32

AB

C

B-1 B-3B-2

C-1 C-3C-2

(1<n<10)

(10<n<26)

Any no. of maps



Mapping


Is the ratio between a length on map to its correspondinglength in field

Types of Scales

Scale:

Very low accuracy

when maps Shrinks

and elongates

Net

Graphical

Numerical

Easy but needs

calculations

لقي س لعددى

طيطختل س يقل

لوط

كبش

Linear

Basic Definitions

e.g. 1:1000

10



Mapping


First: a ruler was designed and drawn on map

- Shrinks and elongates with the map and

faces the same conditions

- Low accuracy

- No calculations needed

Here minimum reading = 5m

105 205 25 30

Trial

Error = 5m

11

Say Scale 1:500

MUST be 1cm

Do not scale



Mapping


Linear Scale

12

Design a linear graphical scale 1:500 with accuracy 1m.

Show a reading 13m on this scale

- No calculations needed

- Overcome Shrinkage and Elongation

- Higher accuracy than ruler but to a certain limit

No. of divisions = Main accuracy

Required accuracy

= 5m

1m

= 5 divisions

Minimum reading = required accuracy

100 5 2015 255 1234

MUST be 1cm

Optional

13

Do not scale

10+3)



Mapping


Measuring distances on a map

13

Show how to use this scale to

measure a distance on map?

100 5 2015 255 1234

1

23

Distance on map

using divider

Distance =13.4m



Mapping


Net (Diagonal) Scale

14

Design a net graphical scale 1:500 with accuracy 0.25m.

Show a reading 12.75m on this scale

100 5 2015 255 1234

4 Hz x 5 VL

5 Hz x 4 VL

10 Hz x 2 VL

2 Hz x 10 VL

Preferred Hz div ≈ VL div.

Complete whole scale

High accuracy

MUST be 1cm

Min on Hz scale = Max on VL scale

12.75

Minimum reading = Required accuracy


Required accuracy

= 5m

0.25m

= 20 divisions

10+2+0.75)

0

0.25

0.5

0.75

1



Mapping

Dr Ahmed Ragheb SCM 221 – Planimetric Surveying 1Lecture 3 15

100 5 2015 255 1234

2

1

Distance on map

Measuring distances on a map

Show how to use this scale to

measure a distance on map? using divider

Distance =13.75m

3

4

5

6

0

0.25

0.5

0.75

1



Mapping


Design a linear graphical scale 1:250 with accuracy 1m.

Instead of 1cm 2.5

m …… m ke

2cm 5m

100 5 2015 255 1234

MUST be 2cm

instead of 1cm

- Scale could be with any NO. and any ACCURACY e.g. 1:25000 with accuracy 10m

- No need to mention linear or net, accuracy will determine scale used based on no.of divisions

- Max no. of Hz divisions = 10

- Nowadays this is done using AutoCAD not manual

16

Notes


Required accuracy

= 2.5m

1m

= 2.5 divisions


Required accuracy

= 5m

1m

= 5 divisions

lecture_3_mapping and scales.pdf

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