Sistem Proyeksi UTM

 Sistem Proyeksi Universal Transverse Mercator (UTM)

Karakteristik Proyeksi UTM :

1. Bidang Proyeksi yang digunakan adalah bidang silinder
2. Kedudukan bidang proyeksi terhadap bidang Datum adalah transversal
3. Kontak bidang proyeksi terhadap bidang datum adalah memotong
4. Sifat distorsi yang dipertahankan adalah konform

Karakteristik UTM

Ketentuan – ketentuan khusu proyeksi UTM :

1. Seluruh wilayah permukaan bumi (Ellipsoid Referensi) dibagi menjadi 60 wilayah, masing-masing wilayah dibatasi oleh dua meridian yang disebut "ZONE UTM"  (lihat gambar 1)
2. Masing-masing ZONE UTM mempunyai koordinat sendiri-sendiri, yaitu : Sumbu X adalah proyeksi ekuator, sumbu Y adalah proyeksi dari meridian tengah tiap zone. Titik potong antara sumbu X dan sumbu Y disebut titik nol (0) sejati. (lihat gambar 2)
3.  Faktor perbesaran pada meridian tengah adalah 0,9996 pad centimeter. (lihat gambar 3)
4. Zone pada proyeksi UTM diberi nomor, yaitu : mulai dari zone 1 (zone yang dibatasi oleh meridian 180 derajat BB dan meridian 174 derajat BB) ke timur sampai zone 60 (zone yang dibatasi oleh meridian 174 derajat BT dan meridian 180 derajat BT). (lihat gambar 4)
5. Batas-batas lintang pada proyeksi UTM adalah 80 derjat Lintang Selatan (LS) dan 84 derajat Lintang Utara (LU), dimana daerah ini dibagi dalam jalur-jalur selebar 8 derajat lintang (pembagiannya dimulai dari 80o LS ke arah utara.
6. Jalur-jalur dengan lebar 8 derajat lintang tersebut diberi tanda dengan huruf-huruf, dimulai dengan huruf C untuk jalur antara 80 derajat LS dan 72 derajat LS, ke utara berturut-turut sampai dengan huruf X (huruf I dan O tidak digunakan).
7. Jalur-jalur dengan lebar 8 derajat lintang tersebut diberi tanda dengan huruf-huruf, dimulai dengan huruf C untuk jalur antara 80 derajat LS dan 72 derajat LS, ke utara berturut-turut sampai dengan huruf X (huruf I dan O tidak digunakan). (Lihat gambar 5)

Gambar 1

Gambar 2

Gambar 3

Gambar 4

Gambar 5

Nomor Zone yang tercakup di Indonesia:Wilayah Indonesia tercakup dalam 9 Zone yakni:

• Meridian : 90 derajat BT - 144 deraja BT
• Lintang   : 06 deajat LU - 11 derajat LS

Kesembilan Zone tersebut adalah:

1. Zone 46  dengan Central Meridian : 93 derajat
2. Zone 47  dengan Central Meridian : 99 derajat
3. Zone 48  dengan Central Meridian : 105 derajat
4. Zone 49  dengan Central Meridian : 111 derajat
5. Zone 50  dengan Central Meridian : 117 derajat
6. Zone 51  dengan Central Meridian : 123 derajat
7. Zone 52  dengan Central Meridian : 129 derajat
8. Zone 53  dengan Central Meridian : 135 derajat
9. Zone 54  dengan Central Meridian : 141 derajat

Apabila bujur suatu titik diketahui, maka kita dapat menghitung Central Meridian menggunakan Rumus:

N = ((B + 183 derajat)/6)

maka:

B = (N x 6) - 183 Derajat

Data Collection Recomendation Using Drones Techonology

 

LEGAL RULES & REGULATIONS

Make Sure you UNDERSTAND ABOUT LEGAL RULES & REGULATIONS IN YOUR COUNTRY ABOUT DRONES BEFORE YOU FLYING A DRONES.

GET YOUR LICENSE TO FLY A DRONE. DRONES IS NOT A TOY !!!!

DISCLAIMER

THIS IS BASED ON EXPERIENCE.

MORE SOURCES YOU GET, MORE GREAT DATA YOU HAVE

GOOD DATA LEADS TO GOOD MAPS. BAD DATA, NOT SO MUCH

Drone Surveying is completely reinventing the way that Land Surveying is being
performed throughout the world. Utilizing a drone for survey projects can produce a better-quality product, in less time, and at a lower cost than traditional surveying methods. However, drone surveying is not right for every project, or every business.

DATA COLLECTION

Proper data collection techniques are the most important factor in creating a great map.

There are a lot of factors that go into collecting imagery with enough overlap and quality to be used in three-dimensional scene reconstruction.

NADIR/TOP DOWN DATA COLLECTION

Suggested Settings for Maps:

Overlap	:	75%/75% (minimum)
Altitude	:	adjusted to the GSD you want to achieve
Time of Day	:	Mid-Day – when the sun is highest in the sky
Conditions	:	Clear, mostly clear or overcast Wind: 0-7 m/s Good, 7-11 m/s Tolerant, 11< m/s Danger to fly
Field Conditions	:	For best results, fields should be freshly tilled or harvested.

 3D DATA COLLECTION

Suggested Settings for 3D Maps:

Overlap	:	75%/75% (minimum)
Altitude	:	adjusted to the GSD you want to achieve
Camera Angel	:	30 degree to 70 degree
Time of Day	:	Mid-Day – when the sun is highest in the sky
Conditions	:	Cloudy, Clear (less shadow), mostly clear or overcast Wind: 0-7 m/s Good, 7-11 m/s Tolerant, 11< m/s Danger to fly
Field Conditions	:	For best results No shadows

 Note: always set up your 3D Mission 2 (two) line before your Area of Interest

 

Suggested Step by step 3D Data Collection:

1.    NADIR/TOP DOWN PHOTO SET

To capture nadir photo, use the same setting as nadir/top down data collection, such as overlap, altitude camera setting etc.

Tips: Use Apps such as pix4d, DJI Pilot, etc.

 

2.    3D MISSION

The most important thing for 3D Mission is about “Shadows”. If its to much shadows/Lights on the object it’s not good for Modeling. So, try to have a good condition of the lights.

Tips: Use Apps such as pix4d, DJI Pilot, etc

1.      Prepare the 3D mission wisely on the apps (Pix4d, DJI Pilot., etc)

2.      Overlap must above 75% for latitude and longitude (75/75).

3.      Altitude is adjusted to the GSD you want to achieve.

4.      Cloudy weather will be Good.

5.      If you have time and the weather with you, make 2 (two) different angles of camera for each mission.

6.      Camera Angle: 70 Degree at Lower altitude and 45 Degree at higher altitude.

 

Example:

-        Nadir Image Capture Altitude: 70 meter AGL

-        3D Mission Image Capture at 70 Degree Camera Angle Altitude: 50 meter – 60 meter AGL

-        3D Mission Image Capture at 45 Degree Camera Angle Altitude: 60 meter – 65 meter AGL

7.      If it's too bright, use Camera Filter.

 

3.    OBLIQUE PHOTO SET

Oblique photo capture for area of interest and object details that are deemed necessary (such as Chimney). For the area of interest, do it with 3 (three) different camera angles and altitudes. The purpose of the 3 different camera angles and altitudes is to get the lower image, midlle image, and upper image that are still connected to each other. Making it easier to merge the image with the Nadir image during processing.

Tips: Use Apps such as pix4d, DJI Pilot, etc or Manual Flights.

A.     LOWER PART OBLIQUE

Circular Mission/Manual Flights with camera angle around 70-80 degree. Some Structure maybe use different approach, such us Structure under the roof or too many uninvolved people (Shopping Centre) the Pilot might be walk with the drones to capture that Structure.

B.     MIDLE PART OBLIQUE

Circular Mission/Manual Flights with camera angle around 60-70 degree

C.     UPER PART OBLIQUE

Circular Mission/Manual Flights with camera angle around 50-45 degree

 

4.    DETAIL PHOTO SET

Using interval time shoot, capture all important detail with high overlap (80 – 90 %).  This type of data capture use for: Roof Detail, Façade, Ortho Elevations and etc.

Tips:

1.      Interval Time Shoot  : 3 Second

2.      Fly speed                : 3 m/s Max

3.      Camera Angle          : 90 Degree

4.      Weather                  : Cloudy (Use filter if too bright)

5.      Don’t Facing the sun when capture images.

6.      Avoid Glare.

7.      Keep the same distance from object and same pattern flights.

8.      In case of narrow space, capture the object using oblique technic from different camera angles and altitude.

9.      For complex detail, Add more lower flight for Nadir/Top down and Oblique (Manual or/and mission flights)

 

5.    OVERVIEW PHOTO SET

Overview photos set aims to connect the entire area between Nadir Image data and Oblique image data.

Things to note are:

1.      The area must be fully covered in circular missions/Manual Flights.

2.      Altitude is recommended not to exceed Nadir/top down Image Altitude.

3.      Camera Angle is recommended at 50-60 degrees.

4.      Flying speed 4 m/s maximum

5.      High overlap (80%) Must be used.

 

Tips:          

1.      Check obstacle before planned the mission

2.      Make sure you always Have VLOS of the drones.

3.      If you can’t do the Overview photo set, try to get more angles and different altitude from Oblique Photo set.

 

COMMON MISTAKE DURING DATA ACQUISITION

There common mistake that pilots most often make in conducting data acquisition for 3D Modeling purposes is "Inconsistent in taking photos". Other things:

o   Forget to check the camera settings (Exposure, B&W Balance, etc)

o   Flying to fast when doing manual flights.

o   Forget to avoid the glare and sun.