# Presentation: 657653

## CORS Concrete Pillar   

**Field Procedures to Establish****CORS Orthometric Heights**

**Curt Smith**
**Denis Riordan**

**CORS Concrete Pillar   **
**Antenna Mount**

## Slide 2

## NDGPS

**NDGPS**

## Slide 4

## http://www.scign.org/

**http://www.scign.org/**

## Slide 6

## Slide 7

## Slide 8

## Slide 9

## Slide 10

## Slide 11

## Slide 12

## Slide 13

## Direct Level Tie from Adjacent Bench Mark to Top of Mounting Surface Sighting Surface

**Direct Level Tie from Adjacent Bench Mark to Top of Mounting Surface Sighting Surface**

**Backsight**

**Foresight**

- BM

## Direct Level Tie from Adjacent Bench Mark to Top of Mounting Surface Using Invar Strip

**Direct Level Tie from Adjacent Bench Mark to Top of Mounting Surface Using Invar Strip**

**Backsight**

**Foresight**

- BM

**Invar Strip**

## 1. Direct Level Tie from Adjacent Bench Mark to Top of Mounting Surface

**Pros**
**Established BF digital level routine**
**Most accurate transfer of elevation**
**Will achieve Second Order, Class 1 or 2 **
**Cons**
**Can’t directly observe to desired surface**
**Antenna in place – move antenna during measurements**
**Digital levels optical system needs to be calibrated**
**Invar strip - plumb and on desired surface**

## 2a. Direct Level Tie from Adjacent Bench Mark to Reference Mark on Monument

**2a. Direct Level Tie from Adjacent Bench Mark to Reference Mark on Monument**

**Backsight**

**Foresight**

- BM

- RM

## 2b. Equipment (?) Measure-up from Reference Mark on Monument to Antenna Mounting Surface

**Constant**

- RM

## Slide 19

## 2. Equipment (?) Measure-up from Reference Mark on Monument to Antenna Mounting Surface

**Pros**
**Accurate transfer of elevation to reference mark**
**Permanent reference mark on monument**
**Cons**
**Currently no established procedures**
**Can’t directly observe to desired surface**
**Antenna in Place – must be moved during measurements**
**“****Conventional Elevation” only to reference mark**
**Unknown accurate distance measuring equipment**
**Equipment and accuracy concerns for measure-up**

## 3a & 4a. Direct Level Tie from Adjacent Bench Mark to Reference Mark at Building

**Backsight**

**Foresight**

**BM**

**RM**

## 3b & 4b. Equipment (?) Measure-up from Reference Mark at Base of Building to Reference Mark on Top of Building

**3b & 4b. Equipment (?) Measure-up from Reference Mark at Base of Building to Reference Mark on Top of Building**

**RM**

**Constant**

## 3c. Direct Level Tie from Adjacent Reference Mark to Top of Antenna Mounting Surface

**RM**

## 4c. Direct Level Tie from Adjacent Reference Mark to Reference Mark at Bottom of Antenna Support Structure

**RM**

**Backsight**

**Foresight**

**RM**

**RM**

## 4d. Equipment (?) Measure-up from Adjacent Reference Mark to Antenna Mounting Surface

**4d. Equipment (?) Measure-up from Adjacent Reference Mark to Antenna Mounting Surface**

**RM**

**RM**

**RM**

**Constant**

## 5. Trigonometric Leveling from Bench Mark to Antenna Mounting Surface

**5. Trigonometric Leveling from Bench Mark to Antenna Mounting Surface**

**Backsight**

**Foresight**

- BM

## 5. Trigonometric Leveling from Bench Mark to Antenna Mounting Surface

**Pros**
**Automatic vertical angles by robotic total stations**
**Draft procedures from Audie Murray and Charlie Glover**
**Cons**
**Can’t directly observe to desired surface**
**Antenna in place – move antenna during measurements**
**Distance limitations (?)**
**Mix of data – conventional/trigonometric leveling**
**Procedures to get data into NGS Database?**

## 6a. Trigonometric Leveling from Bench Mark to Antenna Mounting Surface

**Backsight**

**BM**

**Foresight**

**6a. Trigonometric Leveling from Bench Mark to Antenna Mounting Surface**

## 7a. Trigonometric Leveling from Bench Mark to Reference Mark on Top of Structure

**RM**

**Backsight**

**BM**

**Foresight**

**7a. Trigonometric Leveling from Bench Mark to Reference Mark on Top of Structure**

## 7b. Trigonometric Leveling

**from Reference Mark to**
**Antenna Mounting Surface**

**RM**

**Backsight**

**Foresight**

## 8. Ellipsoid Height Differences Referenced to Bench Marks via GPS Observations

**8. Ellipsoid Height Differences Referenced to Bench Marks via GPS Observations**

## 8. Ellipsoid Height Differences Referenced to Bench Marks via GPS Observations

**Pros**
**Draft procedures from NGS Field Operations **
**Antenna in place – use during measurements**
**Provides GPS/BM in area for geoid modeling**
**Cons**
**Accuracy limitations**
**Will not produce Second Order, Class II elevations**
**Requires bench marks within proximity of CORS**
**Distance limitations (?)**

## Slide 33

## The FGCS Specifications shall apply unless specifically superseded by the requirements specified below.  

**The FGCS Specifications shall apply unless specifically superseded by the requirements specified below.  **
**If there is a conflict between the FGCS Specifications and this document for a given specification or procedure, this document shall take priority.**** **

## Further Study and Development

**Point Identifiers for ARP when establishing Ortho**
**Distance to surrounding bench marks**
**Optional devices for measure-ups**
**Guidelines and specifications for each option**
**Combining multiple measurement systems data**