Keywords: Emission line galaxies (459); Redshift surveys (1378); Spectroscopy (1558)  
1. INTRODUCTION  
2. THE EUCLID-LIKE SAMPLE  
2.1. The WISP Survey  
2.2. The 3D-HST + AGHAST Survey  
2.3. Emission line catalog completeness corrections  
2.4. Sample Selection  
3. EMISSION SIZE MEASUREMENTS  
3.1. Constructing an empirical PSF  
3.2. Modeling Continuum and Line Emission  
4. RESULTS AND DISCUSSION  
4.1. Emission Line Number Counts  
4.2. Emission and Continuum Sizes  
4.3. Equivalent Width of $H\alpha+N\,II$  
4.4. [O III] Line Profile  
4.5. Redshift Accuracy  
4.6. Contaminating Redshifts  
5. SUMMARY